DAC direct vs pre-amp - your opinions please!

[Nyal Mellor]

Interested in who is using their DACs-with-volume-control direct and who is running into a pre-amp.

If you are using a pre-amp, what sonic improvements do you hear, and what volume level were you running the DAC attenuation at?

Particularly interested in the opinions of those using "class A" type DACs like Bricasti, DCS, MSB, etc.

 

[paul79]

There are a couple factors to consider. How the volume control in the DAC keeps the resolution intact at lower settings, and how much drive it has to mate with your amplifier.

To be honest, there are very few DAC's that do not benefit from a very good preamp. The only DAC I have successfully used direct to amps, where a preamp is not necessary, is the Totaldac D1 Dual or the D1 Monobloc. The volume control in these DAC's is very good. With these, if you need a preamp, you seek one that will compliment them, and do no harm to the signal. Again, there are not many that will here either. The NOS Valves NBS is the ONLY cheaper preamp that will do IME, and is a real stunner for what you get for your dollar, or any dollar for that mater. He also offers a cathode follower stage for running hard to drive solid state amps. Otherwise, you are going to spend thousands on a preamp to compliment the Totaldac direct.

 

[ddk]

Interested in who is using their DACs-with-volume-control direct and who is running into a pre-amp.

If you are using a pre-amp, what sonic improvements do you hear, and what volume level were you running the DAC attenuation at?

Particularly interested in the opinions of those using "class A" type DACs like Bricasti, DCS, MSB, etc.

Hi Nyal,

Not every DAC I owned had this capability. I find attenuation in the digital domain is very smooth but not linear, the sound quality changes with volume and is generally bland. Overall every one of them sonically benefited from the preamp.

david

 

[nirodha]

Hi Nyal,

Not every DAC I owned had this capability. I find attenuation in the digital domain is very smooth but not linear, the sound quality changes with volume and is generally bland. Overall every one of them sonically benefited from the preamp.

david

Never missed a pre when using my dCS Elgar Plus directly (using the top MIT cables) into my Spectral monos (360). But then...I have never tried a top Spectral pre...because, as mentioned, I have never felt the need to do so. Have been happy with this setup for at least ten years

 

[edorr]

Never missed a pre when using my dCS Elgar Plus directly (using the top MIT cables) into my Spectral monos (360). But then...I have never tried a top Spectral pre...because, as mentioned, I have never felt the need to do so. Have been happy with this setup for at least ten years

I used the Spectral DMC 30SS Series I with my DMA 360 Series II monos as prescribed by Spectral. Then when I replaced my 360s with the new PS audio BHK 300 monos, I continued to use the Spectral preamp. Just for kicks I ran my PS audio direcstream DAC straight into the mono. No contest. Preamp stays. I had similar experience using the ARC REf 5SE in other setup. However, less then stellar preamps need not apply - used a few cheaper models and DAC direct path beat them.

 

[edorr]

Interested in who is using their DACs-with-volume-control direct and who is running into a pre-amp.

If you are using a pre-amp, what sonic improvements do you hear, and what volume level were you running the DAC attenuation at?

Particularly interested in the opinions of those using "class A" type DACs like Bricasti, DCS, MSB, etc.

I found significant improvement using the ARC Ref 5SE with my MSB DAC when I still owned this gear. Forget the theory on this. You have to try to find out. In my experience, the pre improves "dynamics".

 

[microstrip]

I always found that a properly chosen preamplifier enhanced sound quality - since the old days of the Enlighted Audio Design DSP9000 pro - my first experience with a DAC with volume control. Recently I played with a Wadia 861se, but also preferred the system with a preamplifier.

 

[Mike Lavigne]

I recall back in 2001 when I owned a Mark Levinson top of line amp No. 33/ preamp No. 32; then when I switched the amp to the integrated Tenor 75 watt OTL's I happened to try the internal passive volume control of the Tenors and was very surprised how much better it sounded. the formidable, expensive and beautiful ML No.32 was fairly noisy and micro dynamically a bit thick. I ended up eventually using a passive Placette RVC and a passive custom switchbox for 3 years looking for an active preamp that did not get in the way of the music. I tried a number of pretty high buck preamps which fell short or only equaled the diminutive and cheap Placette....until the battery powered darTZeel NHB-18NS came along.

I had high quality (read very quiet and dynamically alive) sources and overall a low noise system. so anything that got in the way did not work.

a few years ago I purchased a couple of very expensive headphone amplifiers; which were said to work best without a preamp, as they had attenuators. just plug in your source. but in my case they sounded better when I used the dart preamp as the volume control than straight in from my Playbacks Design.

so it's all about the context in which the preamp is working. and the noise floor and dynamic 'life' of the sources, the power grid, the room, and the amp.

the brand new dart pre is quite a bit lower noise and higher dynamics than the one it replaced.

I don't think you can generalize as to what is best; it's all a matter of context. the dart pre and others like it are not cheap......

 

[ddk]

I recall back in 2001 when I owned a Mark Levinson top of line amp No. 33/ preamp No. 32; then when I switched the amp to the integrated Tenor 75 watt OTL's I happened to try the internal passive volume control of the Tenors and was very surprised how much better it sounded. the formidable, expensive and beautiful ML No.32 was fairly noisy and micro dynamically a bit thick. I ended up eventually using a passive Placette RVC and a passive custom switchbox for 3 years looking for an active preamp that did not get in the way of the music. I tried a number of pretty high buck preamps which fell short or only equaled the diminutive and cheap Placette....until the battery powered darTZeel NHB-18NS came along.

I had high quality (read very quiet and dynamically alive) sources and overall a low noise system. so anything that got in the way did not work.

a few years ago I purchased a couple of very expensive headphone amplifiers; which were said to work best without a preamp, as they had attenuators. just plug in your source. but in my case they sounded better when I used the dart preamp as the volume control than straight in from my Playbacks Design.

so it's all about the context in which the preamp is working. and the noise floor and dynamic 'life' of the sources, the power grid, the room, and the amp.

the brand new dart pre is quite a bit lower noise and higher dynamics than the one it replaced.

I don't think you can generalize as to what is best; it's all a matter of context. the dart pre and others like it are not cheap......

You're talking about a passive analog attenuation Mike different animal from attenuation in the digital domain.

I had the same Levinson 33/32 combo you had and ended up selling it too. It sucked because I had the 33/31.5/30.5 for years waiting for the 32 to complete the Reference chain and one remote! I had it for less than two months before selling it all and moving on to Lamm.

david

 

[microstrip]

You're talking about a passive analog attenuation Mike different animal from attenuation in the digital domain.

I had the same Levinson 33/32 combo you had and ended up selling it too. It sucked because I had the 33/31.5/30.5 for years waiting for the 32 to complete the Reference chain and one remote! I had it for less than two months before selling it all and moving on to Lamm.

david

David,
You should have stopped at the 31.5/30.5/380s/20.5. I listened to a great system using these components - a bit on the dark side, but musical.

 

[ddk]

David,
You should have stopped at the 31.5/30.5/380s/20.5. I listened to a great system using these components - a bit on the dark side, but musical.

You know how these things go micro… or at least used to go back then. I had the CJ Premiere Seven with that system, should have never sold it!

david

 

[Mike Lavigne]

You're talking about a passive analog attenuation Mike different animal from attenuation in the digital domain.

never was ever going to happen for me.....attenuation in the digital domain that is.

I had the same Levinson 33/32 combo you had and ended up selling it too. It sucked because I had the 33/31.5/30.5 for years waiting for the 32 to complete the Reference chain and one remote! I had it for less than two months before selling it all and moving on to Lamm.

david

that (2001) was right when I first met you and purchased my Kharma's from you, and although I slightly preferred the Tenor OTL's to the Lamm then, that was my other consideration.

 

[ddk]

never was ever going to happen for me.....attenuation in the digital domain that is.

I gave it a shot just to see, didn't last long.

that (2001) was right when I first met you and purchased my Kharma's from you, and although I slightly preferred the Tenor OTL's to the Lamm then, that was my other consideration.

I remember it well Mike, been a while but went by in a flash...

david

 

[microstrip]

You know how these things go micro… or at least used to go back then. I had the CJ Premiere Seven with that system, should have never sold it!

david

Really great sounding preamplifier - I upgraded it myself to Seven B with parts supplied by Lew Johnson. Although I later sold it I still keep a box of 6CW4 nuvistors somewhere! But I remember that both the 6GK5's and the 6CW4 could easily become noisy.

 

[ddk]

Really great sounding preamplifier - I upgraded it myself to Seven B with parts supplied by Lew Johnson. Although I later sold it I still keep a box of 6CW4 nuvistors somewhere! But I remember that both the 6GK5's and the 6CW4 could easily become noisy.

You should have left it as the "a" version. But we're digressing from the main topic here.

david

 

[Brian Walsh]

A pre amp should be audibly transparent, so there should be no difference.
A pre amp should have a low output impedance which may suit the high input impedence of your power amps.
Keith.

Heavy emphasis on "should," which isn't always the case. With correct impedance matching it is possible to not use a preamp. For example, the Bricasti M1 DAC used direct into their M28 monoblock amplifiers is an amazing match. But when you want to listen to other sources such as vinyl, a really good preamp can work well.

 

[Fitzcaraldo215]

In my all digital Mch setup, I use no preamp. It is Exasound e28 directly to the amps via xlr. I have not tried a preamp with the Exasound, and I see no need to. There are absolutely no issues I can hear with dynamics or with volume control tracking. My typical volumes range from -5 to -15 dB per the Exasound readout. I believe that digital volume control for signal in the digital domain can be virtually perfect, exceeding even the very best analog volume controls. Not much could be simpler than putting a 24 bit signal into a 32 bit buffer, then successively truncating least significant bits to attenuate volume without loss of the original 24 bit resolution. Only random noise is thrown away in the truncation.

Yes, line stages are supposed to be completely transparent, but good ones are not quite so in practice, particularly with the addition of analog cables and connectors in the signal path.

Before my Exasound, I was using a Mch prepro into a Levinson 380 S in HT bypass mode for the front channels. The Levinson was used for stereo sources such as vinyl, etc. The Levinson sounded very good on its own in stereo. But, even though the Levinson volume control was bypassed in HT mode, I found that the Mch sound going through it was lacking in transparency vs. removing it from the circuit entirely. I have given up some input flexibility from removing it, but the sonic improvement was well worth it.

 

[edorr]

In my all digital Mch setup, I use no preamp. It is Exasound e28 directly to the amps via xlr. I have not tried a preamp with the Exasound, and I see no need to. There are absolutely no issues I can hear with dynamics or with volume control tracking. My typical volumes range from -5 to -15 dB per the Exasound readout. I believe that digital volume control for signal in the digital domain can be virtually perfect, exceeding even the very best analog volume controls. Not much could be simpler than putting a 24 bit signal into a 32 bit buffer, then successively truncating least significant bits to attenuate volume without loss of the original 24 bit resolution. Only random noise is thrown away in the truncation.

Yes, line stages are supposed to be completely transparent, but good ones are not quite so in practice, particularly with the addition of analog cables and connectors in the signal path.

Before my Exasound, I was using a Mch prepro into a Levinson 380 S in HT bypass mode for the front channels. The Levinson was used for stereo sources such as vinyl, etc. The Levinson sounded very good on its own in stereo. But, even though the Levinson volume control was bypassed in HT mode, I found that the Mch sound going through it was lacking in transparency vs. removing it from the circuit entirely. I have given up some input flexibility from removing it, but the sonic improvement was well worth it.

I tired a few MCH analog preamps. None makes the cut to actually improve SQ. I found the Theta Sex SHooter to be completely transparent (no deterioration) though. I currently run two DACs directly into center channel and surrounds with no analog pre in between, and an analog preamp in the signal path for my mains (manually set at unity gain volume level when I play MCH sources), which as I reported before improves SQ.

 

[Nyal Mellor]

Thanks for the feedback!

 

[dallasjustice]

I directly compared some very excellent preamps to a totaldac. The totaldac was better. I used a Veloce LS-1 and Krell 202. The amps at the time were Krell 900e and the connections were the Krell CAST connections. I felt the Krell 202 was better than the LS-1. But the totaldac was better without any preamp for sure. I have no reason to believe my results would have been any different with many other fine quality digital frontends. I now use Jriver for volume control and I am very happy.

There are two potential issues with digital volume control:
1. Gain matching. The gain of the DAC needs to be set within a range where you are not using more than -20db-30db of attenuation. If one uses too much attenuation, then dynamic range will suffer a bit. Of course, this depends on the room's actual dynamic range. Many excellent listening spaces don't have anymore than 90db of dynamic range. In my system, I use no more than -15db of attenuation at good listening levels. Many excellent DACs have the ability to set the voltage. I would recommend finding one of those DACs so that you can have some flexibility with different amps. Also, many consumer DACs offer max 2v RMS output on both SE'd and XLR. IME, this is too little voltage. I believe one needs more than that to get volume up high enough in most systems. Of course, this varies from system to system, depending on the amps, speakers and room.
2. Output impedance. The DAC needs sufficiently low output impedance to drive the amps. I don't have any specific answers with regard to absolute levels, but I would look for a DAC which has something say 100ohms or less. IMO, anything more than 100ohms could modulate the frequency response of the DAC into some lower input impedance amps.

If these issues are properly addressed and the digital volume control uses 32 bit or 64 bit floating point precision with dither, I don't see how any analog pre-amp could offer any performance gain.