Differences in sound: DAC vs. DAC + Pre-amplifier

[One and a half]

There are exceptions for preamplifier with very little noise and still provide switching flexibility.

Interior craftsmanship and know how to keep paths short are not mysterious but takes some experience.

This one looks very much like my preamp, btw.

 

The photo below is from Luxman if google is correct.

 

 

[Ralf11]

On 2/5/2020 at 9:16 PM, Rexp said:

The pre amp used to be THE most important component in a high-end system with solid state ones hard to find. Good ones I've had were made by ATC, Gryphon, Parasound and Simaudio. No idea whats on offer now but they wont be cheap. 

 

you must mean "THE most [electronic] important component" - speakers have always been the real issue

 

Audio Research is still around and doing fine; Mac has one or more, Accuphase and many others still manf. pre-amps

[fas42]

13 hours ago, sandyk said:

???

 A decent preamp these days rarely needs more than perhaps a quality multi position ceramic switch with several wafers,(or relay input control) and a decent attenuator such as a Goldmund, DACT or Khozmo 48 position. It shouldn't matter if non selected inputs are terminated or not ,when both sides of the selected input are switched through. It should also have a relatively low gain of perhaps 3 times .

 Most high quality preamps these days don't use tone or balance controls , and shouldn't need to.

 Neither should they need Tape Outputs either, which also simplifies switching, or need an RIAA  Phono stage.

 

Note that I was responded to a post that that said "used to be THE most important" ... in previous times it was the go to have lots of options on a preamp, or integrated, of lower cost. That NAD unit I'm using was pretty rough in SQ when I got it - most of the really objectionable crappiness disappeared when I ripped all the switching, etc, out of the signal path.

 

I started to get the SQ I'm interested in when using an extremely simple setup - zero preamp type facilities ... so I would always go back to that arrangement, effectively, to see what the inherent capability of the chain was - and then assess whether the losses of adding desired switching and attenuation capability was acceptable or not.

[fas42]

3 hours ago, Ralf11 said:

 

you must mean "THE most [electronic] important component" - speakers have always been the real issue

 

 

I think there needs to be an epiphany at some point in the life of each audio enthusiast, when they realise that this is incorrect - luckily, this happened for me over three decades ago; and so I just smile when I'm subjected to the awfulness of the sound coming through some mega-expensive speaker - "It's not your fault, Mr Speaker!" ... 😝.

 

When you can get sound that "makes you smile" over a "junk" speaker, then you realise where the priorities really lie ...

[fas42]

13 hours ago, One and a half said:

There are exceptions for preamplifier with very little noise and still provide switching flexibility.

Interior craftsmanship and know how to keep paths short are not mysterious but takes some experience.

This one looks very much like my preamp, btw.

 

The photo below is from Luxman if google is correct.

 

 

 

Just came across this one, the Mola Mola Makua,

 

This is one that, visually, says to me that it should be of a high order.

[fas42]

And, I note in this thread review, that the right things are being said about the subjective performance,

https://www.stereo.net.au/forums/topic/117214-mola-mola-dac/

 

[photonman]

I have had my Benchmark DAC3 for almost two weeks now and could not be happier.  It is great to have hardware volume control just for the convenience and control.  The Benchmark is a no nonsense black box made out of bent sheetmetal and all in all it sounds very good to me.  My setup is very simple:  Mac to DAC to Amp.  The OP's question is really hard to quantify with results and it all is a balance and wants and needs.  I am sure I could get better sound but for my wants, the sound has not suffered with this remedial DAC/Pre combo.  I am also very happy that I now have balanced analog out to my class d amp.  The volume control for digital into this DAC is in the digital domain.  Vice versa if you use it as a preamp, analog in would have volume control in analog domain.

[Kimo]

8 minutes ago, photonman said:

I have had my Benchmark DAC3 for almost two weeks now and could not be happier.  It is great to have hardware volume control just for the convenience and control.  The Benchmark is a no nonsense black box made out of bent sheetmetal and all in all it sounds very good to me.  My setup is very simple:  Mac to DAC to Amp.  The OP's question is really hard to quantify with results and it all is a balance and wants and needs.  I am sure I could get better sound but for my wants, the sound has not suffered with this remedial DAC/Pre combo.  I am also very happy that I now have balanced analog out to my class d amp.  The volume control for digital into this DAC is in the digital domain.  Vice versa if you use it as a preamp, analog in would have volume control in analog domain.

 

I have talked with Benchmark and they indicated that the best measured performance was obtained by using the DAC at a fixed volume and employing their preamp.  They also said the improvements were only really noticeable on things like reverb trails and only on certain recordings, so you are really digging deep at that point.  

 

Generally speaking, your SNR will suffer with the insertion of a preamp, but you may still prefer it for other reasons.   

[Miska]

6 hours ago, Kimo said:

I have talked with Benchmark and they indicated that the best measured performance was obtained by using the DAC at a fixed volume and employing their preamp.

 

At least they can sell more devices by saying so...

 

[barrows]

OK, here is my take.  Please feel free to disagree with me, but do not tell me I am wrong.

 

I first tried no preamp, with a Buffalo DAC (DIY) using the first generation "Legato" I/V stage, and the preamp was a highly capable Ayre K-5xe-MP.  The results were:

 

With preamp, higher noise floor, a little less transparency, but better dynamics and fuller, more robust sound.  I preferred with preamp, but wanted to figure out DAC direct as it was clear there was an advantage in transparency with DAC direct.

 

Then, the designer of the Legato output stage changed it, tripling its output current capability.  I now tried DAC direct vs. preamp again:

 

DAC direct: lower noise floor, better detail retrieval, and now, no loss of dynamics either.  So now that the DAC was driving the input stage of the amplifier optimally, there was only loss by adding the preamp.

 

After about 3 weeks of testing, i sold my Ayre preamp, and have not looked back.

 

It is clear to me that DAC direct, for those who do not need source switching. results in the best fidelity to the source, as long as the DAC's output stage is capable of driving the amplifier input stage robustly.  Additionally, most DACs have the capability to drive most amplifier input stages entirely adequately.  Look for a DAC with low output impedance (less than 100 ohms is nice, but up to a couple hindered ohms is going to be OK for most amps) and enough output voltage.  Most IC opamps in DAC output stages can drive amps directly with no problem.  Occasionally there might be a DAC with a bit weaker output stage, but these are rare.

 

I would advise that taking advice direct from manufacturers who sell preamps might not be the best way to make decisions on this, as those manufacturers have an interest in selling preamps.  One really needs to listen in their own system, to the DAC, Preamp, and amplifier one is considering, to decide for sure.  And, definitely do not take advice from "old skool" audiophiles who just claim that any serious audio system must include a pre amp (for no good technical reason), this is a quaint and antiquated notion which has no basis in reality.

 

There is one addition i would make here:  I have heard the claim that adding a preamp can reduce the high frequency noise from the DAC, leading to "blacker" backgrounds.  This supposition relies on the idea that preamps typically will have low pass filters on their inputs, to avoid RF getting into the circuitry.  OK, this is possible, but a couple of things to consider if you think you are hearing this:  DACs all have low pass filters on their outputs, and well designed DACs should not have a lot of high frequency noise on their outputs.  Power amplifiers also usually have a low pass filter right at their input to avoid RF getting into the amp.  My conclusion is that with competently designed DACs and Amplifiers, there should not be any noise problem going DAC direct which would benefit from adding a preamp as an additional filter element between DAC and Amp.  But, there are probably cases of poorly designed DACs, and/or poorly designed amplifiers where adding a preamp actually helps because of this low pass filter effect.  If this happened to me though, i would want to determine what component was poorly designed and allowing this to be the case.

[jabbr]

16 minutes ago, barrows said:

It is clear to me that DAC direct, for those who do not need source switching. results in the best fidelity to the source, as long as the DAC's output stage is capable of driving the amplifier input stage robustly.

Totally agree. The DIY Pass B1 buffer eg this version: https://diyaudiostore.com/products/mezmerize-b1-buffer could help but a good DAC should have a robust output stage. I mention this because this output stage can be configured to become a sweet little output filter for the DAC.

[craighartley]

20 minutes ago, barrows said:

OK, here is my take.  Please feel free to disagree with me, but do not tell me I am wrong.

 

I first tried no preamp, with a Buffalo DAC (DIY) using the first generation "Legato" I/V stage, and the preamp was a highly capable Ayre K-5xe-MP.  The results were:

 

With preamp, higher noise floor, a little less transparency, but better dynamics and fuller, more robust sound.  I preferred with preamp, but wanted to figure out DAC direct as it was clear there was an advantage in transparency with DAC direct.

 

Then, the designer of the Legato output stage changed it, tripling its output current capability.  I now tried DAC direct vs. preamp again:

 

DAC direct: lower noise floor, better detail retrieval, and now, no loss of dynamics either.  So now that the DAC was driving the input stage of the amplifier optimally, there was only loss by adding the preamp.

 

After about 3 weeks of testing, i sold my Ayre preamp, and have not looked back.

 

It is clear to me that DAC direct, for those who do not need source switching. results in the best fidelity to the source, as long as the DAC's output stage is capable of driving the amplifier input stage robustly.  Additionally, most DACs have the capability to drive most amplifier input stages entirely adequately.  Look for a DAC with low output impedance (less than 100 ohms is nice, but up to a couple hindered ohms is going to be OK for most amps) and enough output voltage.  Most IC opamps in DAC output stages can drive amps directly with no problem.  Occasionally there might be a DAC with a bit weaker output stage, but these are rare.

 

I would advise that taking advice direct from manufacturers who sell preamps might not be the best way to make decisions on this, as those manufacturers have an interest in selling preamps.  One really needs to listen in their own system, to the DAC, Preamp, and amplifier one is considering, to decide for sure.  And, definitely do not take advice from "old skool" audiophiles who just claim that any serious audio system must include a pre amp (for no good technical reason), this is a quaint and antiquated notion which has no basis in reality.

 

There is one addition i would make here:  I have heard the claim that adding a preamp can reduce the high frequency noise from the DAC, leading to "blacker" backgrounds.  This supposition relies on the idea that preamps typically will have low pass filters on their inputs, to avoid RF getting into the circuitry.  OK, this is possible, but a couple of things to consider if you think you are hearing this:  DACs all have low pass filters on their outputs, and well designed DACs should not have a lot of high frequency noise on their outputs.  Power amplifiers also usually have a low pass filter right at their input to avoid RF getting into the amp.  My conclusion is that with competently designed DACs and Amplifiers, there should not be any noise problem going DAC direct which would benefit from adding a preamp as an additional filter element between DAC and Amp.  But, there are probably cases of poorly designed DACs, and/or poorly designed amplifiers where adding a preamp actually helps because of this low pass filter effect.  If this happened to me though, i would want to determine what component was poorly designed and allowing this to be the case.

Does your DAC have a volume control, or are you using fixed output and something like HQPlayer to control volume?

[barrows]

3 minutes ago, craighartley said:

Does your DAC have a volume control, or are you using fixed output and something like HQPlayer to control volume?

I have more than one DAC, some have volume controls, and sometimes I may control volume in software.  

 

So, on volume controls:  Digital Volume control, in software on a computer, or in in hardware on most DAC chips, is generally going to perform better than most analog volume control implementations.  As long as one does not need huge amounts of attenuation (more than -40 dB or so).  If one is listening at very low levels, small details will be below the noise floor anyway, so at high levels of attenuation one is not missing anything.  Despite many audiophile myths to the contrary, there is nothing about digital volume control when well implemented (at 32 bits or more, with a properly matched system gain structure).

 

What a lot of people seem to ignore in the discussion of volume controls is the analog volume controls are far from "perfect", they add noise and distortion to the signal of their own.  Digital volume control is actually more transparent than analog within it s limits:

 

Consider a 32 bit volume control in the digital domain, and a 24 bit source file:

 

32-24= 8 bits, so with a 32 bit volume control one has 8 spare bits to use with no impact on resolution.

 

8*6=48, so one has -48 dB of volume reduction before any resolution (of our 24 bit source file) has been lost, this means there is no problem here!

 

Then consider that most volume controls in software are running at 64 bits!

 

Then consider that actual i room dynamic range of a system is never better than 16 bits...  So in our above example there are actually 16 bits of resolution we can lose without any audible consequences, so we really have 16*6=96, -96 dB of reductio possible with our 32 bit volume control without any impact on real world resolution in room.

 

One can see that there is no "problem" with digital volume control. 

[craighartley]

3 minutes ago, barrows said:

I have more than one DAC, some have volume controls, and sometimes I may control volume in software.  

 

So, on volume controls:  Digital Volume control, in software on a computer, or in in hardware on most DAC chips, is generally going to perform better than most analog volume control implementations.  As long as one does not need huge amounts of attenuation (more than -40 dB or so).  If one is listening at very low levels, small details will be below the noise floor anyway, so at high levels of attenuation one is not missing anything.  Despite many audiophile myths to the contrary, there is nothing about digital volume control when well implemented (at 32 bits or more, with a properly matched system gain structure).

 

What a lot of people seem to ignore in the discussion of volume controls is the analog volume controls are far from "perfect", they add noise and distortion to the signal of their own.  Digital volume control is actually more transparent than analog within it s limits:

 

Consider a 32 bit volume control in the digital domain, and a 24 bit source file:

 

32-24= 8 bits, so with a 32 bit volume control one has 8 spare bits to use with no impact on resolution.

 

8*6=48, so one has -48 dB of volume reduction before any resolution (of our 24 bit source file) has been lost, this means there is no problem here!

 

Then consider that most volume controls in software are running at 64 bits!

 

Then consider that actual i room dynamic range of a system is never better than 16 bits...  So in our above example there are actually 16 bits of resolution we can lose without any audible consequences, so we really have 16*6=96, -96 dB of reductio possible with our 32 bit volume control without any impact on real world resolution in room.

 

One can see that there is no "problem" with digital volume control. 

Thanks for this, which is very interesting. I'd like to use digital volume control, but the problem I've found is that software (eg Roon with HQPlayer) limiting of maximum volume is unreliable, so my speakers are laid vulnerable to potential damage.

[barrows]

16 minutes ago, craighartley said:

Thanks for this, which is very interesting. I'd like to use digital volume control, but the problem I've found is that software (eg Roon with HQPlayer) limiting of maximum volume is unreliable, so my speakers are laid vulnerable to potential damage.

I have not found that to be the case with a dedicated machine as the server (not on Windows though, some have reported that Windows can be a problem for this).  With ROON running on Mac OSX or Linux I have never had a volume control "incident".  I have only used HQPlayer briefly, so cannot reliably comment on that, but Jussi (miska) seems to believe HQP volume control is stable on Linux.

If one is using a computer for general purpose and running a software player on it at the same time, that could result in problems I guess...

[craighartley]

13 minutes ago, barrows said:

I have not found that to be the case with a dedicated machine as the server (not on Windows though, some have reported that Windows can be a problem for this).  With ROON running on Mac OSX or Linux I have never had a volume control "incident".  I have only used HQPlayer briefly, so cannot reliably comment on that, but Jussi (miska) seems to believe HQP volume control is stable on Linux.

If one is using a computer for general purpose and running a software player on it at the same time, that could result in problems I guess...

Thanks for this. I do have a dedicated server (Roon on a Mac Mini streaming to HQPLayer on a dedicated machine running the HQPlayer OS), and I'll have another try. My problem occurred when I changed some settings in HQPlayer and (without me noticing) this wiped the volume limit I had set in Roon.

[barrows]

14 minutes ago, craighartley said:

Thanks for this. I do have a dedicated server (Roon on a Mac Mini streaming to HQPLayer on a dedicated machine running the HQPlayer OS), and I'll have another try. My problem occurred when I changed some settings in HQPlayer and (without me noticing) this wiped the volume limit I had set in Roon.

Yeah, there is no doubt that one has to be a bit careful.  I always have a "standby" function on my amps which is easily accessible, and mutes the output.  So if I ma doing anything which might cause problems, I ma sure to mute the amp first, then I double check everything as a matter of course, then un-mute the amp.  Of course one can make a mistake with an analog volume control as well.  

[fas42]

3 hours ago, barrows said:

It is clear to me that DAC direct, for those who do not need source switching. results in the best fidelity to the source, as long as the DAC's output stage is capable of driving the amplifier input stage robustly.  Additionally, most DACs have the capability to drive most amplifier input stages entirely adequately.  Look for a DAC with low output impedance (less than 100 ohms is nice, but up to a couple hindered ohms is going to be OK for most amps) and enough output voltage.  Most IC opamps in DAC output stages can drive amps directly with no problem.  Occasionally there might be a DAC with a bit weaker output stage, but these are rare.

 

I would advise that taking advice direct from manufacturers who sell preamps might not be the best way to make decisions on this, as those manufacturers have an interest in selling preamps.  One really needs to listen in their own system, to the DAC, Preamp, and amplifier one is considering, to decide for sure.  And, definitely do not take advice from "old skool" audiophiles who just claim that any serious audio system must include a pre amp (for no good technical reason), this is a quaint and antiquated notion which has no basis in reality.

 

 

Amen. First good rig had CDP with digital volume, output impedance of 100R, no trouble driving the power amp - in fact, the Perreaux was the component that started to lose it at higher sound levels.

 

An inadequate analogue volume control can easily kill any chance of achieving convincing SQ ... the weakest link scenario.

[Miska]

On 3/1/2020 at 9:47 PM, craighartley said:

Thanks for this. I do have a dedicated server (Roon on a Mac Mini streaming to HQPLayer on a dedicated machine running the HQPlayer OS), and I'll have another try. My problem occurred when I changed some settings in HQPlayer and (without me noticing) this wiped the volume limit I had set in Roon.

 

When you use HQPlayer, it is better to set volume limit in HQPlayer. If you enable "Direct SDM", volume control becomes disabled because you are asking bit-perfect pass-through for DSD data, but this is indicated in the main window because the volume knob becomes disabled as result too.

 

[craighartley]

35 minutes ago, Miska said:

 

When you use HQPlayer, it is better to set volume limit in HQPlayer. If you enable "Direct SDM", volume control becomes disabled because you are asking bit-perfect pass-through for DSD data, but this is indicated in the main window because the volume knob becomes disabled as result too.

 

I can’t see where to set a volume limit in HQP Embedded; only where to set startup volume. 

[Miska]

15 minutes ago, craighartley said:

I can’t see where to set a volume limit in HQP Embedded; only where to set startup volume. 

 

On Embedded volume configuration needs manual adjustment of the configuration file as there are some extra parameters that can be set to deal with software volume and software + hardware combination volume.

 

There are "volume_min" and "volume_max" attributes in the configuration file under "engine" element. Default values are min=-60 and max=0.

 

[craighartley]

46 minutes ago, Miska said:

 

On Embedded volume configuration needs manual adjustment of the configuration file as there are some extra parameters that can be set to deal with software volume and software + hardware combination volume.

 

There are "volume_min" and "volume_max" attributes in the configuration file under "engine" element. Default values are min=-60 and max=0.

 

Okay. The trouble is that I’m using the bootable image so that I can leave the server headless (and inaccessible) and don’t have to deal with altering it other than via the web interface. 

[craighartley]

52 minutes ago, craighartley said:

Okay. The trouble is that I’m using the bootable image so that I can leave the server headless (and inaccessible) and don’t have to deal with altering it other than via the web interface. 

I’ve now realised I can set the volume limit by editing the xml file produced by Backup and then ‘restoring’ it. I don’t need to access the machine directly. 

[ro7939]

On 2/5/2020 at 12:19 PM, plissken said:

Preamps can obviously color the sound. They can't however improve the fidelity of the inputs.

 

So says someone who never heard of an impedance mismatch.  

[ro7939]

My understanding is that all digital VC is of the bitstream variety only.  There is no such thing as a digital volume in DSD format, hence the only potential VC for such application is of the analog type.  Another way to say this is that the exclusive use of a digital VC disallows DSD file playback.  I find it curious that this has apparently been ignored up to now in this conversation, but I apologize if I missed it.

 

There also appears to be a wide range of debate as to what is an "adequate" ratio of output impedance to input impedance; hence what person A may call a "robust" source for a given load someone else would call "fail."  I've heard 10-1 ratio is appropriate (less is not), but for others the ratio is much higher (I fall into the latter group).  I searched long and heard for preamps in the past couple weeks, and the only preamp vendor I found that specifies minimum load impedance was deHavilland (kudos to them; I bought the Kinki Studio EX-P7 Goldmund Edition SS preamp).    

 

I suspect someone making absolute statements to answer the OP is akin to person A stating a concrete minimum amplifier power suitable for person B.  There are too many variables.  People hear differently.  Two persons can hear the same thing and describe the differences similarly, and make mutually exclusive value judgements.     

 

There are just so many variables including the length and type of IC cables, and the fact that changing the amp (load) can change the input/output ratios and hence the performance product.

 

I prefer to use among the best music playback software (HQ Player) and hardware dedicated only for music playback (NUC) > low-moderate cost DAC with fixed full level analog output > power amps (which in my case includes two kilowatt sub amps each w/12k input impedance; the total load may drop below 9k ohm depending on the main amp).  This allows easy swapping of DAC and power amp, with the preamp taking care of input/output impedance matching under any and all condition.

 

I'm currently pretty darn happy with the "lowly" $400 Pro-Ject Pre Box S2 DAC in the above system.  

 

My personal experience strongly contradicts the above stated math touting the performance advantage of digital VC (beyond the fact that there's no such thing as DSD VC): 

A: $10k Bricasti M1 SE DAC, digital variable volume @ -12 dB > power amp 50k input Z

B: $10k Bricasti M1 SE DAC, fixed 0 dB gain > Pioneer VSX-D01 Elite TXH receiver pure analog inputs -12 dB (don't laugh, the analog stage is good) > same power amp as above 

 

B thoroughly outperformed A by big margin, throughout, no exceptions.  I went back and forth at least 3x. 

 

BTW, Re. the performance level of the M1 DAC: I have a decent quality SACD player.  I did this AB test.  The music program in both cases was a well recorded Alison Kraus Live, dual layer SACD/Red Book:

A: SACD player analog output > preamp

B: Same SACD player playing the same disc, but this time the Red Book layer, coax digital output > Bricasti M1 > preamp (VC lower for same SPL, SACD level is attenuated vs. Red Book).

 

B totally incinerated A, almost sounded like a different performance, a shocking improvement.  I state this to show the M1's performance level relative to the earlier described AB test.  

 

Yes, as someone stated, one can err Re. an analog VC.  The difference is that with many preamps, a visual glance can confirm the volume setting, whereas in the digital realm some invisible software setting can be off, and take a lot longer to find and fix than a glance across the room.