Does a DAC need a pre-amp

[gradier]

I am playing my music collection (ALAC files) through JRiver and listening via an IFI IDAC2 and M-Audio M-38 powered monitors. Right now, I have to use the mouse on the computer to control volume (the IDA2 does not have  volume control for the RCA OUTS). Is this a scenario where I would benefit from having a pre-amp? If it had volume control, that would be a possible benefit, but my real question is this: Is there any advantage from the point of view of sound to adding a preamp to the chain between the DAC and the powered speakers?

[GUTB]

You don't "need" a pre-amp's analog's volume control circuit to control volume -- you can rely on JRiver and/or the iDAC's driver (if it allows for device volume control) will do this.

 

You will need a good ANALOG pre-amp to get the best sound quality, though.

 

If you're going to build out your system eventually, a nice pre-amp as the core  is a not bad place to start.

[gmgraves]

11 minutes ago, gradier said:

I am playing my music collection (ALAC files) through JRiver and listening via an IFI IDAC2 and M-Audio M-38 powered monitors. Right now, I have to use the mouse on the computer to control volume (the IDA2 does not have  volume control for the RCA OUTS). Is this a scenario where I would benefit from having a pre-amp? If it had volume control, that would be a possible benefit, but my real question is this: Is there any advantage from the point of view of sound to adding a preamp to the chain between the DAC and the powered speakers?

The main answer is that generally speaking, the shorter the path, the cleaner the sound. Any additional active circuitry that you place between your source and your speakers will definitely compromise SQ. The question then becomes (1) can or can you not actually hear the insertion loss in real listening situations, and (2) is any loss of SQ worth the added advantage of being able to control the volume conveniently?

Some will tell you that a passive volume control is all you need (such as the one sold by Schiit), but I hesitate to make such a suggestion because most passive volume controls are merely potentiometers in a box. These not only vary the volume, they also vary the source impedance that the power amp sees. Most source components have a very low output impedance of less than 600 Ohms (usually), and most amps have input impedances of 10K Ohms or greater. The output of a simple pot, may (or may not) mess with the amp's frequency response. The exception is if, instead of a pot, the control is a true "T-Pad". Then there would be no impedance mismatch, but these are few and far between. If you decide to try a passive volume control, my advice is to use the shortest connection between the control and the amplifier possible. Between the source and the pot, the distance is not critical, but it can very well be between the pot and the amp. I hope this helps.

[Speed Racer]

My experience is that a quality active preamp sounds better than no preamp or a passive preamp.  

[sandyk]

12 minutes ago, Speed Racer said:

My experience is that a quality active preamp sounds better than no preamp or a passive preamp.  

 

 WTF !!!

We are in complete agreement on this occasion.

 

A decent Preamp is usually better able to drive modern Power Amplifiers, which these days often have lower Input Impedances of typically around 10 Kohms, in order to assist with reduced D.C. offset at their Output etc. They also have a much lower output impedance and increased current driving capabilities, as well as often being able to properly drive a quality pair of headphones from their dedicated headphone output jack.

A few CD/DVD/BR players however,do also have a proper Buffer stage (low impedance) at the output which is better suited to driving the later Power Amplifiers, as well as making them less susceptible to Interconnect vagaries.

 

Quote

. The output of a simple pot, may (or may not) mess with the amp's frequency response. The exception is if, instead of a pot, the control is a true "T-Pad". Then there would be no impedance mismatch, but these are few and far between. If you decide to try a passive volume control, my advice is to use the shortest connection between the control and the amplifier possible.... George

 

As George has recommended, use the shortest possible cables from a Passive Preamp to reduce HF rolloff.

[plissken]

To flip this a bit:

 

What posters are saying is that the volume control via software is a decimating control that reduces the bit-depth as you turn the volume down in the player application. 

 

Good analog controls don't do this.

 

What I did is get a DAC in the first place that didn't force me into such a compromise because by the time you take the price of the iFi and add a decent external analog attenuation to it you could have taken that entire budget and just purchased a unit that had it all in. 

 

Many others and myself have been able to do this because we are just down to one source: A computer. My Emotiva DC-1 has both fixed output and pre-amp mode. It's pre-amp mode uses it's own inbuilt analog ladder. 

 

A lot of pro-audio interfaces get this right also. Heck even my now 'ancient' 2008 EMU-1212M PCIe that I picked up for $85 NIB, via it's virtual mixer had a non-decimating volume control. I'm surprised that modern audiophile products are designed the way they are and still somehow command a steep price for the shortcomings. 

[TubeLover]

1 hour ago, Speed Racer said:

My experience is that a quality active preamp sounds better than no preamp or a passive preamp.  

+100

 

A good quality active preamp, in my experience, improves the sound in virtually every system. I've heard some VERY high dollar systems that did sound fine direct from the DAC to the amp, but we are talking $20k+ DAC's, and monoblock amps also in the range of $20k each. And I still strongly suspect that a great preamp would have improved those too.

 

JC 

[Ralf11]

given the system the OP has, he might try the least expensive tubed pre-amp that Schiit offers while turning the software volume all the way up (use the pre-amp to adjust volume)

 

tubed gear often offers some euphonic characteristics, and Schiit will let him return it for a nominal fee if he doesn't like it

[Fitzcaraldo215]

There is no one right answer to the question of whether a digital volume control is/is not "better" sounding than an analog control in a preamp or a passive one.  It all depends on the implementation, but proper implementation is not rocket science.  However, some manufacturers may nonetheless screw this up. 

 

Theoretically, a digital control is better, provided it uses sufficient bits. A 16 or 24 bit signal as the MSBs in a register of 32 bits or more is typical and prevents loss of any audible bit depth resolution as volume is reduced in most situations.  Even many inexpensive HT AVRs use 32 bits for this reason, discarding LSBs consisting only of random noise as volume is reduced.

 

That plus the DAC analog output should be impedance and output level compatible with the amps without straining, which should be no big deal in this day and age.  Except, it seems not all manufacturers get this.  And, passive analog volume controls violate this as an electronic necessity.

 

For decades, I have found that the introduction of additional analog stages to the signal path inevitably introduced some loss of transparency.  Expensive preamps were better in this regard and their degradation less noticeable, but the issue was still there. No getting around the fact that good analog volume controls are expensive.  Excellent, totally transparent, digital volume controls are much cheaper to produce.

 

I myself am quite happy with the 32-bit digital volume control in my Exasound e28, which is integrated with the digital volume control in JRiver via the DAC's driver.  It drives my amps directly and  flawlessly. My maximum playback output levels typically are in the -5 to -15 dB range  per my DAC or JRiver display, though calibrated  individual channel level trims are applied by Dirac Live in my 7.1 setup.

 

 I have heard absolutely no reason to insert a preamp into my system.  The only reason might be to be able to select other players or sources not on my PC.  But, I do not do that, and it would involve loss of the use of Dirac EQ in my PC.

[pkane2001]

26 minutes ago, Fitzcaraldo215 said:

For decades, I have found that the introduction of additional analog stages to the signal path inevitably introduced some loss of transparency.

 

That mirrors my experience, exactly. I spent a long time looking for a preamp that would be beneficial in multiple systems I've built. I've not found one. From tube preamps to solid state to hybrids, all muddled the sound stage to some degree, caused frequency distortions, made playback less transparent. Perhaps there's some combinations of DACs and amps that do benefit from an active stage for impedance or level matching, but I've not run into this situation with any of my systems.  

 

If you can get away with not using a preamp, that would be the best way to go. And if you do feel like you do need a preamp, it may be worth it to try to figure out if there's something not properly matched in your system between the DAC and the amp... or, perhaps that you just prefer the euphonic distortions added by the preamp.

[GUTB]

2 hours ago, Fitzcaraldo215 said:

There is no one right answer to the question of whether a digital volume control is/is not "better" sounding than an analog control in a preamp or a passive one.

 

There is one right answer -- digital is not better than an analog preamp.

[GUTB]

1 hour ago, pkane2001 said:

 

That mirrors my experience, exactly. I spent a long time looking for a preamp that would be beneficial in multiple systems I've built. I've not found one. From tube preamps to solid state to hybrids, all muddled the sound stage to some degree, caused frequency distortions, made playback less transparent. Perhaps there's some combinations of DACs and amps that do benefit from an active stage for impedance or level matching, but I've not run into this situation with any of my systems.  

 

If you can get away with not using a preamp, that would be the best way to go. And if you do feel like you do need a preamp, it may be worth it to try to figure out if there's something not properly matched in your system between the DAC and the amp... or, perhaps that you just prefer the euphonic distortions added by the preamp.

 

Have you tried a preamp that costs more than $50?

[kumakuma]

5 minutes ago, GUTB said:

 

There is one right answer -- digital is not better than an analog preamp.

 

We've been down this road before:

 

You were wrong then and you're wrong now.

[GUTB]

Just now, kumakuma said:

 

We've been down this road before:

 

You were wrong then and you're wrong now.

 

Let's try this from a different direction...

 

 

This is a line level preamp, the BAT REX. See all that stuff inside? What's the purpose off all those parts?

[pkane2001]

Just now, GUTB said:

 

Have you tried a preamp that costs more than $50?

 

Yes. But, I'm fascinated by your approach to audio: the more expensive, the better the sound must be? What a simple solution to all the audiophile dilemmas!  

[kumakuma]

3 minutes ago, GUTB said:

 

Let's try this from a different direction...

 

 

This is a line level preamp, the BAT REX. See all that stuff inside? What's the purpose off all those parts?

 

 

Justifying the 25K price?

 

What's your point?

 

[GUTB]

7 minutes ago, kumakuma said:

 

 

Justifying the 25K price?

 

What's your point?

 

 

So all that stuff is for photo ops -- just audio cosmetics?

[kumakuma]

5 minutes ago, GUTB said:

 

So all that stuff is for photo ops -- just audio cosmetics?

 

 

Are you saying that the simple fact that someone sells a 25K preamp packed full of expensive parts proves your point?  In my opinion the existence of this preamp simply proves that there are people out there who will buy something like this.

[pkane2001]

5 minutes ago, GUTB said:

 

So all that stuff is for photo ops -- just audio cosmetics?

 

Looks sexy, no argument! It's a bit less impressive if you consider that a straight wire between a DAC with a digital volume control and the amp can do a better job. 

 

[Speed Racer]

26 minutes ago, pkane2001 said:

 

Looks sexy, no argument! It's a bit less impressive if you consider that a straight wire between a DAC with a digital volume control and the amp can do a better job. 

 

 

That is just plain incorrect. But you keep thinking that.......

[pkane2001]

Just now, Speed Racer said:

 

That is just plain incorrect. But you keep thinking that.......

 

Prove me wrong.

 

[gmgraves]

15 hours ago, Speed Racer said:

My experience is that a quality active preamp sounds better than no preamp or a passive preamp.  

 

You are misinterpreting what you have experienced*. Every active stage adds distortion. It's a fact of life. it has to be, there are no if ands and buts about it. Now, it is possible that the distortion in a modern preamp is so low that you don't notice it, but if you measured the chain from the source to your speakers, an active preamp will measure poorer than a passive one (or no preamp at all). Like I said, passive volume controls like the Schiit SYS, can cause frequency response problems with some amps. After all, as the specs for the SYS say the maximum output impedance for the control is 5KΩ. With an amp that has an input impedance of 10KΩ (which is typical) a variable source impedance can alter the frequency response curve. This would make the system sound worse than an active preamp where the controls are buffered and present the power amp with a constant low impedance load.  

 

* Interesting how misinterpretation of observed data can result in mythology so entrenched in society's consciousness that it is taken almost as gosple. Take, for instance, the old wives tale that one's hair and nails continue to grow after death. It's nonsense, but people will tell you that they've observed the phenomenon. What they have really observed is the shrinking of skin after the blood (no longer circulating) pools at the body's lowest point. as the skin shrinks it pulls away from the nails and the hair. making it look like a man's beard has grown since he died, thus giving him a 5 O'clock shadow that he didn't have at the moment of death, and fingernail that seem longer than they were at the moment of death. To the casual observer, it looks as if these have continued to grow. They haven't. 

[Speed Racer]

1 minute ago, pkane2001 said:

 

Prove me wrong.

 

 

All of my experience proves you wrong......

[kumakuma]

4 minutes ago, Speed Racer said:

 

That is just plain incorrect. But you keep thinking that.......

 

Suggest that you read some of the posts in the thread I linked to above. Both Miska and Barrows disagree with you.

[pkane2001]

2 minutes ago, Speed Racer said:

 

All of my experience proves you wrong......

 

I'm guessing that you realize that this is no proof at all. I have no way to examine or to judge your experience or to compare it to my own, which very clearly disagrees with yours.