Misleading Measurements

[March Audio]

On 4/22/2021 at 11:05 AM, stereo coffee said:

But preamp line level outs are adding reactance. this is absolutely fine if you also resign to not ever wanting to hear what your source can actually provide.

 

Instead far better is to always design around not adding reactance other than minor contribution of cabling, which is to always have sensitivity of your power amp close to consumer line level - lets say below 500mv RMS and then be enabled to use resistance attenuation. The ability to experience the capability your source component is the desired result with any audio system, putting layers in between to satisfy difference to consumer line level, that you think is adding something,  is abstract at best.   

 

The Quad 306 I think being the best example of a power amp, being from a manufacturer of considerable experience ( since 1936 ) has sensitivity of 0.375mv RMS   ... perfectly matching consumer line level... they knew what they were doing. 

    

Reality is that the vast majority of modern consumer digital sources have an output of, or very close to, 2V rms at 0dBFS.  It's been this way for years.  This may not be a "standard" but it certainly is the current convention.

 

Most equipment is now designed around and work with this level. The 0.316V level is effectively redundant.  The vast majority of power amps sit between 25 and 30dB gain as a result.

 

As an example one of our ower amps would require 43dB of gain to reach full power output (425 watts into 4 ohms) if the signal input was limited to just 300mV.  This amount of gain is bad noise levels, the 2 volt current convention is far more sensible.

 

Can you explain what you mean by "adding reactance"?  In an active pre amp the input impedance will be unrelated to the output impedance. 

[March Audio]

2 hours ago, stereo coffee said:

Indeed players have that capability, but the media played remains strictly and sensibly at consumer line level at 0.316V RMS....

 

Reactance can be described as inertia against the flow of current, notably contained naturally in the electrical properties of capacitors and inductors. Reactance is added to a circuit,  by any such component in a circuit particularly in the signal path. A review of schematics of active pre's will locate,  how many reactance components,  they use in order to pass signal from input to output.  

 

 

   

 

 

With respect you have a misunderstanding about this.  The signal level is entirely dependant upon how loud you turn the volume, and of course the level at any given moment in the recording.  With modern digital sources it will be at any level between 0v and 2 volts rms.

 

Thanks for your explanation but I know what reactance is, I was really looking for some kind of explanation of why you think it's "bad".

 

[March Audio]

2 hours ago, stereo coffee said:

You only need to attenuate consumer line level,  which is NOT 2v RMS its nominal 0.316v RMS  , You might be reading too many reviews that test equipment at that high level, that is unrelated to what is at a RCA socket when playing CD's in home audio systems. 

 

Why its bad is because your source component contains the very best opportunity of presenting music as it actually can be, adding anything in-between other than resistance to attenuate,  simply detracts from that opportunity.    

Sorry, but you have a fundamental misunderstanding of whats going on.  As explained consumer line level is *not* 0.316 volts rms.  The vast majority of modern digital sources are 2 volts rms at 0dBFS. 

 

The actual required signal voltage for any final acoustic volume level depends upon the pre / power amplifier gain and the speaker sensitivity.  It will not be 0.316V.  0.316 V is a meaningless number.

 

It doesnt follow that other ("reactive") components damage signal quality.  In fact filters are a fundamental and necessary part of audio reproduction.  They do "good", they are not bad.  They are there for a reason.

[March Audio]

4 hours ago, stereo coffee said:

But no they are rarely if ever measured at -10dBV -RMS , and they should be, that is the point. one only has to go back a few posts to find: 

 

Consumer line level is already adhered to by some manufacturers, Quad as example selling approximately 2500 units, of their 306 power amplifier all with sensitivity at 0.375V RMS 

 

 

Can you show me some dacs that don't output 2 volts rms (or very close to) at 0dBFS?

 

Better still can you show me some dacs that output 0.375v at 0dBFS?

 

The Quad 306 is nearly 40 year old design. Modern components do not adhere to this 300mV level.

 

After CD became established domestic line level quickly changed to the 2 volt convention we have now.  It's been thatxway for literally decades.

[March Audio]

3 hours ago, bluesman said:

Both you and MarchAudio appear to be confused about “line level” in consumer audio devices.  It is both -10 dBV and 2 volts, depending on how you spec it. The mean level as measured on an averaging scale is the -10 dBV that you seem to think is the only proper spec, which equals your 0.316 volts.  But consumer line level can also be defined by the maximum peak voltage before clipping and distortion set in, and that (for analog signals) is usually +6 dBV, which equals 2 VRMS.  Not all equipment reaches the upper limit of its distortion spec at exactly the same level, so analog peak line voltage can be spec’ed a bit higher or lower in some equipment. But you’re all talking about the same specification!

 

Some engineers and manufacturers choose to design equipment to a different performance level.  This is irrelevant as long as the line out voltage range is enough (but not too much) to drive the next device(s) in the signal chain to a normal range of listening levels and preserve a reasonable range of gain control.  It is not an indication that the design team failed to understand the concept of line level.

 

So the same consumer line level is correctly stated as -10 dBV average and/or +6 dBV peak.  These are specs for the maximum level at rated distortion that is available to drive the next stage.  Remember too that this is the output voltage from the last line stage, so the associated specs for distortion etc describe the signal as it exits the device through a line output.

Can you show any specs of output voltage of audio equipment where it is measured as "mean level"?

 

I can't say I have ever seen an AC voltage measured in any circumstance in any field as its mean and for good reason.   The mean of the voltage levels in a sinusoidal waveform is zero!

 

This is why rms is used.

[March Audio]

BTW if anyone is confused between Volts, dBV and dBU you can look at converters such as this

 

http://www.sengpielaudio.com/calculator-db-volt.htm

 

[March Audio]

22 minutes ago, bluesman said:

All such specs are measures of a mean voltage.  Another name for RMS voltage is the quadratic mean voltage.  The -10 dBV RMS value of 0.316V is the quadratic mean of the signal level voltage swing.  If the test signal is a steady sine wave, there are no peaks - the mean voltage over time is the same as the peak voltage.  
 

Measuring line level voltage by applying a pure sine wave to the input is done with a voltmeter or other measuring device across the output.  True RMS measurement is an averaging of the voltage over a certain period of time.  As the test tones used for this are steady, the instantaneous voltage is the same as the mean voltage over time.

 

But for dynamic program material like music, the peak level is the highest instantaneous RMS voltage level in the signal over time, and the (quadratic) mean voltage is the average RMS voltage over time.   Following your logic, a voltmeter set on averaging would always read zero regardless of the AC voltage drop across it - but it doesn’t.

 

 

No they are not.  RMS is not the same as just mean.

 

A sinusoidal waveform has (identical) positive going values and negative going values.

 

"The mean is a type of average. It is the sum (total) of all the values in a set of data, such as numbers or measurements, divided by the number of values on the list."

 

The mean of a sinus is zero. 

 

 

Put as many values as you like into this, put as many cycles as you like into this, the sum is zero, the mean is zero

 

 

As I asked earlier please show me anywhere that ac voltages are represented as just the mean value.

 

[March Audio]

26 minutes ago, March Audio said:

9 minutes ago, bluesman said:

I’m sorry to seem contrary, but I don’t know how else to say this - you’re simply wrong.  The quadratic mean (also called root mean square and abbreviated as RMS) is another type of average. It measures the absolute magnitude of a set of numbers, not their arithmetic average.  So every RMS voltage measurement is an average by definition.  Not all means are simple mathematical means.

 

This horse has now been pronounced dead.

 

 

With respect the simple example above shows that I am correct.  Its basic maths.

 

As I said RMS is not the same as just mean.  You can look at it as representing the area under the curve or the "heating value".  This is why its important when looking at non sinusoidal signals which may have significant crest factors.

 

To think of RMS an an "average" reading is quite misleading.

 

Anyway, in the context of this discussion there is no way 2 volts rms can be represented as 0.316v mean as you asserted.

[March Audio]

25 minutes ago, The Computer Audiophile said:

Thanks for disagreeing politely guys and for getting back to the discussion at hand. 

I think it simply a case of Stereo Coffee thinking that the "consumer level" convention of -10dBv (0.316v rms) - and I say convention because I dont think its been enshrined in any formal standard - is still being used.

 

It may have been prevalent in the 1970s, but no-one uses it now and havent for decades.

[March Audio]

1 hour ago, lucretius said:

 

Correct me if I'm wrong, but there is a big difference between nominal output voltage (e.g. 0.316v rms) and maximum output voltage. The spec sheets for consumer equipment* these days show the maximum output voltage,  somewhere around 2 Vrms (sometimes a little less and sometimes a little more).

 

*My Mytek Brooklyn DAC+  apparently has a maximum output (at 1kHz) of 9.84V from the balanced outputs.

The Mytek is a little unusual in that it has output options which make it flexible across professional and domestic applications.  We have a RME ADI2 Pro FS BE which has +4,+13,+19 and +24dBu output options (1.22V, 3.46v, 6.9v and 12.2 volts rms respectively).  However the vast majority of normal domestic dacs will be 2 volts rms from RCA and 4 volts rms from balanced outputs (if they have them) at 0dBFS.

 

This doesnt mean the level is 2 volts all the time, it depends on whats going on in the recording.  Music usually has a low rms level compared to its peak, maybe a ratio of 1:5.  Recordings are very often normalised so that their peak is up to 0dBFS.  This will be a typical peak voltage of around 2.8 volts.

[March Audio]

Oh just to add that your dac may have a volume control which makes the output voltage obviously variable.

[March Audio]

2 hours ago, stereo coffee said:

Which happens to be used in the majority of audio equipment, in use today, ie those having RCA connectors.  

 

 

-10 dBV Standard voltage reference level for consumer and some pro audio use (e.g. TASCAM), equal to 0.316 Vrms. (Tip: RCA connectors are a good indicator of units operating at -10 dBV levels.)

With respect this is simply incorrect.

 

Well I can only suggest you take a test signal at 0dBfs and measure the voltage at the RCA output of a range of dacs to test if your opinion is correct.

 

You will find they are nearly all around 2 volts rms.

 

If you don't believe me please take a visit to Audio Science Review where there are tests of probably a hundred plus dacs that show this to be the case.

 

Can I ask if you have a dac or CD player and if so what make and model it is?

[March Audio]

47 minutes ago, bluesman said:

Wow - this is news!  So the maximum volume level of the transient peaks in most music is about 5 times the level of the bulk of its content.  We should name that ratio because it seems so useful.  Let’s figure out a good name together.

 

Maybe there’s a way to measure and specify the two parameters in your 1:5 ratio.  The 1 is the general overall level of the main sonic content of music - that sounds kinda sorta like it could be the average level. The 5, which represents the level of the highest peak, is an instantaneous measurement we could call (drum roll please...) the peak.  How about calling it the average-to-peak ratio?

 

Hmmmm - I just noticed the curious coincidence that the ratio between -10 dBV and +6 dBV is in the general range of 1 to 5.  Perhaps, per rule #39 of Leroy Jethro Gibbs, there are no coincidences.  

1:5 is very much a generalisation, it depends on the music.  I will post some examples later.

[March Audio]

57 minutes ago, bluesman said:

You don’t need to post examples. Of course it’s a generalization, just as “consumer line level” specs are generalizations.  And the 0.316 / 2 volt spec pair is a generalized compromise reflecting real world use.  But the concept is what’s important in this discussion.  Whether you call it usual, general, average, mean or something else, common use of a design spec for a common operating parameter that serves as a proxy for the amplitude of your music at your usual listening level helps to assure compatibility among multiple brands and designs of devices.  In this case, we’re discussing the general loudness of your music during playback when the device being measured is in the optimal part of its operating range.
 

You missed my point, which is that the concept of an average level vs a peak level is exactly what is defined by the -10 dBV / +6 dBV line level spec.  The quadratic mean (yes - mean!) of the audio signal passing through your system (measured as RMS voltage) when you play music is the “usual” level during playback at the point of measurement.  At line level outputs, it’s in the range of -10 dBV (0.316 vRMS).  As there is no mandated standard for this, line levels vary from design to design - but few consumer preamps ignore or vary very much from the 0.316 / 2 volt ratio because few amplifiers have input sensitivities far enough from the norm to be unusable with this range of input signal levels.  Yes, there are exceptions just as there are audiophiles who listen at average SPLs far above or below the usual range.

 

The proof of the pudding is that we don’t have to buy one preamp, DAC, amplifier etc for quiet listening, one for our usual level, and one for loud playback.  We don’t have a chamber music amplifier and a hard rock amplifier.  Conformity with the general line level range (defined by -10 dBV for usual / average / overall SPLs at the speakers driven by almost any amplifier and +6 dBV for the highest peak level at rated distortion and totally unclipped) makes most front end devices compatible with most power stages.

 

This is all based on one’s average listening level, which is measurable all along the signal chain from first analog input transducer (cartridge, tape head, DAC etc) through each interface all the way to the listening position (where it’s measured as SPL in acoustic dB).
 

Once the electrical signal is transduced into mechanical energy by the speakers, it becomes audible and we measure it as the average SPL coming from your speakers.  And there too, we use both average and peak measurements to define the operating range.

Sorry but there is no "usual level" and there is no reason to relate it to 316mV.  You seem to be conflating "a level you may listen at" with a technically defined sensitivity.

 

The level required to playback at any particular volume will depend on multiple factors including pre / power amp gain and speaker sensitivity.

 

[March Audio]

The Quad 306 was mentioned earlier.  Typical of amp designs from that era (ie pre cd)  it had high sensitivity.

 

50 watt output into 8 ohms amp.

Input of 375mV required to drive it to 50 watts into 8 ohms.

50 watts into 8 ohms requires 20volts which is a gain of 34.5dB.

 

This old amp is close to conformance with the -10dBv convention.

 

Most modern power amps are only around 26dB gain (it does depend on their power output) because line levels have shifted to 2 volts.  Just do a bit of reading on amp spec pages to confirm this is the case.

 

[March Audio]

6 hours ago, bluesman said:

I let the edit function time out - here’s the rest of the story:

 

The range and distribution of the SPLs in the first part of my response are the acoustic energy analogues of the same mathematical functions derived for line level voltages in the system while listening - so the usual range of listening levels is mirrored by the usual signal levels in the signal path during listening.  
 

A distribution function is defined by location, consistency, scale, shape, and skew.  Location is determined by measures of central tendency - mean, median and mode. Scale is the range of highest and lowest values.  The shape of a distribution like this is determined by its symmetry around the chosen measure of central tendency (skew) and the standard deviation of the value set (variability).

 

An audio engineer’s choice of line level at preamp outputs is based on the above.  Despite your assertion that there is no usual average SPL for audiophile listening, there is clearly an average range - and the choice of line levels near the top of the range for rated distortion and other performance specs (~0.316 and ~2 VRMS for average / usual / habitual / common / often used listening levels from most analog consumer power amplifier stages) is made to accommodate average use by the average buyer.

 

You have actually confirmed what I have said.

 

I didn't say there was no average listening level, although obviously it varies dramatically, I was referring to signal source level, whichvis what this conversation is about.

 

Question for you.

 

Assuming a desired listening level of 85dB spl, calculate the signal source level when:

 

1. Speaker sensitivity is 84dB/2.83v/m and amplifier gain is 24dB

 

2. Speaker sensitivity is 92dB/2.83v/m and amplifier gain is 30dB.

 

Domestic set ups can easily fall within this range.

[March Audio]

2 hours ago, stereo coffee said:

You have identified precisely why misleading measurements persist, particularly in the forum you mention. 

here is the Audio Engineering Society    https://www.aes.org/par/d/#decibel    definition of what you refer to: 

 

0 dBFS A digital audio reference level equal to "Full Scale." Used in specifying A/D and D/A audio data converters. Full scale refers to the maximum peak voltage level possible before "digital clipping," or digital overload (see overs) of the data converter. The Full Scale value is fixed by the internal data converter design, and varies from model to model. [According to standards people, there's supposed to be a space between "dB" and "FS" — yeah, right, like that's gonna happen.]

 

The same level ability though is not occurring at the RCA outputs of CD players, when playing CD's, because they always comply with consumer line level 0.316V RMS  

 

The peak level of 0.316V RMS is  0.447V RMS  , and the Peak to Peak of 0.316V RMS is 0.894V RMS 

 

You can see compliance to those levels here, RMS is in light blue , and peak in dark blue. 

 

 

 

 

 

 

With respect there is nothing misleading going on here, it is simply a misunderstanding on your behalf.

 

I will do my best to explain.

 

You have posted the correct definition of a full scale signal and yes it is exactly what s happening at a CD player or dac RCA output.  However I would go as far to say that no modern cd players or dacs have a line level output of 316mV.

 

Im afraid your plot does not demonstrate compliance.  It does not show that its voltage on the verticle scale and you are using music as a test test signal.

 

You simply cannot use music as a test signal to assess the line level output of a device.  You will get completely different results if you used say a quite piano concerto that was only recorded up to -10dBFS compared to a highly compressed death metal track that constantly hitting 0dBFS.

 

You *have* to use a consistent signal at a defined level; a sine wave at 0dBFS.

 

Here is a Gustard X16 that happens to be on my bench playing a 0dBFS 1kHz signal.  Output from the RCA is 2 volts RMS / 5.8v pk to pk.

 

 

[March Audio]

It sounded just fine.  You certainly will have recordings that hit 0dBFS.

 

Here is Amorok, I didnt search out the loudest segment just grabbed a small section around 6 minutes in.

 

767mV rms, 5.11 mV pk to pk

 

I could easily find louder recordings than this.

 

 

 

[March Audio]

43 minutes ago, stereo coffee said:

The fuss is IMO about levels we find available on CD's DVD's blurays etc . The levels being measured with equipment bear no relationship at all,  being absurdly 6.33 times higher. 

 

Mike Oldfields Amarok is the loudest CD I own, but it still has peaks that accommodate consumer line level.    Hence the effort I consider is to start seeing reviews of equipment that match the variety of media we enjoy. We are hopefully collectively now able to see the fabrication of measuring equipment at 0DBfs that is NOT consumer line level we enjoy from our CD's DVD's etc which is 0.316V RMS. Yes sure the equipment can reproduce such level with test CD's , but few of us would enjoy or have in our collections sine waves at 0DBfs, rather what we have is CD's DVD's etc with music,  that rigidly sticks to consumer line level.  

 

Below is Mike Oldfields Amarok, we can see the level gets to extend to the absolute peak to peak value of consumer line level, which is  0.894V, Vpp , and as can be seen explains visually why it is the loudest CD I own    

 

The secondary fuss is about sensitivity of power amps also matching to consumer line level. If this is done we can then just use resistance attenuation in between, and get in theory as close as possible to what our source has with capability at its output RCA.   We should instead be talking about ideal shunt and series resistances - as  Ike Willis said in Frank Zappa's Thing fish ... moving the project forward 

 

Can you tell us what CD player you are playing that back on and how you have calibrated Audacity to read volts?

 

Have you just loaded that track into audacity without actually playing it back from the CD player and calibrating to read volts?

[March Audio]

23 minutes ago, stereo coffee said:

But was that from the CD player output, or from your preamps output ?  You should find direct from your CD player it remains within consumer line level.  

As the picture shows it was directly from the rca socket on the dac.

 

Please take on board all the evidence shown. As I mentioned please go to ASR and look at the hundreds of dac tests that show they nearly all have a 2 v rms output (or very close to) at 0dBfs and that none have 316mV output at this level.

 

This means that with music, outputs will peak up to about 2.8volts or 5.6 volts pk to pk.  The RMS level will be dictated by the music style, content and recording techniques (compression)

[March Audio]

28 minutes ago, stereo coffee said:

The DAC tests are as I see, nothing more than  1khz sine waves, hence alien & unrelated to consumer line level music signals.  

They are at 0dBFS.  Most recordings are normalised so they peak close to 0dBFS as this provides the highest signal to noise ratio.

 

Therefore music recordings will peak close to 2.8 volts or 5.6 volts peak to peak.  The rms level will be dictated by the music style, content and recording techniques (compression).

[March Audio]

2 hours ago, stereo coffee said:

My scope is old school, but I have it selected to display 0.5v per division @ 0.5ms we can see playing Amarok it occupies close to 2 divisions on peaks  meaning audio signal from my Sony Cd player is outputting as expected at 0.316v RMS and 0.894 Vpp

As already explained you can't use music to accurately measure the line level output voltage.  Was that even a loud section of the track? 😉

 

What model cd player is it?

 

Even the very first cd player, the Sony cdp101 had a line output of 2 volts.

 

[March Audio]

3 hours ago, stereo coffee said:

And no dynamics, and sounding squashed will be the direct result. Why ASR is pushing this agenda is the question to ask, as it has nothing to do with enjoyment of music. 

 

I will start a new thread, as its a fascinating subject, there i will provide answer to what is needed.  

 

On what basis do you make this claim?  Can you explain in more detail?

 

There is no agenda.  I am at a loss as to why you wont accept the fact that the signal voltages are higher than you believed.  I am also at a loss as to why you think that directly leads to "no dynamics"  Its just a higher voltage.  The dynamics are the same.

 

Please do start a new thread as I think we have probably exhausted discussion here and your beliefs are not relevant to the topic of "misleading measurements".

[March Audio]

1 hour ago, bluesman said:

I don’t want to continue beating my head against a stone wall here.  But the most recent posts have injected a new level of misinformation and confusion that has me screaming inside my head - and I have to relieve the pressure.

 

You can not commingle traditional dB measurements and terms with dBFS (or dB FS, since the omission of the space upsets one participant despite the fact that almost everyone omits it). The “full scale” unit of measurement is ONLY used for digital signal levels in digital equipment.  It is a totally different metric from the rest, which are to be used ONLY for analog signals in analog equipment.

 

0 dBFS is the maximum possible level in a digital audio signal.  There is no + side on the scale because it’s a rigidly defined metric whose ascending scale ends at 0.  There is no headroom above 0,  there is only a scale below it.  There is no “line level” standard for it and it is not useful in any way in listening to, calibrating, measuring, describing, or designing analog equipment.

 

The full scale metric is potentially useful to audiophiles ONLY in systems that are fully digital to the output stage.   The level of a digital signal is not measurable in volts because it’s not an electrical signal - it’s a series of numbers.  It is a continuous measure - it’s purely binary, and it cannot be amplified.  Level changes are effected only by interchanging 0s and 1s in the strings of them that ARE the signal.  
 

Unlike analog signals, digital signals have no property that can be used directly to generate electrical or physical output.  Electrical power and its components are measurable and controllable properties that define an analog audio signal and are manipulated to turn the low amplitude outputs from source devices into signals identical in nature and configuration but with sufficient power to push them into your ears and brains.  Digital signals have no such properties and require conversion to analog representations so we can hear them.

 

Once you drop a digital device into a signal path, you throw all convention out the window.  No measurement system exists to define signal levels.  And once you go completely digital (to the output stage, since there has to be D-A conversion to make our primitive brains perceive the information as sound), you can no longer use any of the metrics that have some of you so upset.  
 

Analog metrics are only useful in analog systems to measure analog signals.  Once you inject any interconversion to and from the digital domain, there are no applicable metrics or standards.  And the entire debate here over line level is both irrelevant and erroneous except when discussing purely analog signals and systems.  That’s why I used the term analog as a descriptor in every post on this topic in this thread.  

Sorry but I have to disagree.  You appear to have a misunderstanding.

 

Digital signals are turned into analogue signals. They don't exist in isolation. This cannot be a totally arbitrary process because you would not be able to have different pieces of equipment correctly operating with each other.

 

The perfect example of this was when CD came out its output levels were significantly higher which caused issues for many amps overloading them and caused volume controls to operate over a very limited range.

 

Yes dBFS indicates the highest digital signal level but this is directly relateable to the highest analogue signal level that exits a dac or cd player.  So it's absolutely relevant. You must have standards, or at least conventions on what this level will be.

 

Knowing this level ( 2 volts with current convention) is essential information that allows you to correctly design the following pre / power amplifier.  To have the correct gain level

[March Audio]

7 hours ago, bluesman said:

Of course they do, just as this post exists in isolation.  Digital signals are pages of words that can be read, duplicated, edited, printed on paper, archived, etc.  They aren’t “turned into” analog signals - they’re used as a template for the creation of de novo analog signals whose vacillations reproduce encoded patterns of change to a level of accuracy determined by sampling rate, bit depth etc.

 

The process of DA conversion is conceptually like the process of amplification.  The signal on a record, CD or other source is not turned into the signal that powers your speakers.  It’s used as a template to modulate a totally different current flow to change as the source signal changes.  But both current flows exist as independent entities - and the characteristics of the source determine characteristics of the output.  Both sources exist as independent entities, the digital signal as a series of 0s and 1s and the analog signal as undulating grooves pressed into vinyl, etched by lasers into pits on the undersurface of a plastic platter, etc.  You can’t hear a digital file and you can’t hear record or CD - but you can hear their content as above.

 

A DAC uses a digital word stream to modulate a DC source into a replica of the waveform it encodes.  Analog audio devices use tubes, transistors etc to modulate DC current into a replica of the input waveform.  Digital amplifiers push the conversion process to the power stage.  But it’s all the same concept - an input signal is used to shape a separate and distinct output signal.  A digital file is as real as a vinyl disc - and it’s as useful in isolation.

 

You can’t listen directly to a digital signal.  You have to transform its content into an energy form you can sense and understand.  This is what your audio system does.  You can’t read this post with your eyes closed.  You have to transform its content into an energy form you can sense and understand.  This is what your visual system does.  The blind have to do it another way, eg using Braille to convert content into tactile input.

 

This ain’t rocket science.

Sorry but Im really lost as to what point you are trying to make here.  No-one has said you can listen to digital data.  The whole conversation is about how these digital word values get turned into analogue voltages - specifically what voltage level.

 

With respect you have a massive misunderstanding if you think that DACs (digital to analogue converters) dont turn digital word values into analogue voltages.

 

Digital word values are turned into voltages.  Each word value has a discrete voltage level.  As has been shown with modern dacs and CD players if playing a 16bit word the highest value 0dBFS (111111111111111 in a16 bit signed system) gets turned into 2.8 V with the current convention for RCA domestic connections. 

 

So of course these digital word values are directly relatable to an analogue voltage.