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Any comments on DAC directly to Power amp with no

Do you have any comments of running a DAC directly to power amplifier with no preamp? I can think of several advantages to not using a preamp but would really like your opinion, since, it seems, many of us are opting to go direct these days.

For example, let us assume the DAC goes straight into the power amp's XLR inputs; the DAC's volume control is digital, runs in 32 bits (or 24bits) and is very well implemented.

I have been told that some users do not like the idea of running a volume control well down in its range so use fixed attenuators but many have reported a loss of SQ in the process. Others have stated that they prefer the sound through a preamp stage. And, as expected, others state the sound quality is improved when the preamp is eliminated.

I hope to test these options, with and without the pre-amp, shortly and am interested in hearing about your experiences.

Any comments on this would be appreciated.
hgeifman
georgehifi's avatar
georgehifi
10,312 posts
 
08-18-15: Hgeifman
I am not going to run my DAC direct into my integrated amplifier. I have been told that most DAC’s do not supply as much drive as a properly designed preamplifier.

Don't want to stir up a debate, but whoever told you this about your Ayre QB-9 DSD DAC is way way off the mark!!
As I have said it will deliver from it's 2v SE or 4v XLR at a very low 71ohm source impedance, this is better drive than most preamps can deliver, especially tube ones.

And a volume control done in the digital domain of a dac is superior if it's used at 75% or higher of it's range, that why I suggested you use the 2v se output, as most amp will clip (reach full output) at 2v input.

Cheers George
hgeifman OP
2,108 posts
 
Georgelofi, Thanks for your comments and do not worry about the stirring up the debate. My Ayre QB-9 DSD DAC does not have a volume control so I cannot use it. I am getting a Bricasti M1 DAC loaner that does have a volume control. As suggested above, I will test the M1 with a pre-amplifier and also run it direct into my integrated ampliifer. RCA plugs are required to separate the pre-amp from the Luxman 590ax amplifier.

Unfortuniately, I CANNOT use my balanced cables from the DAC to my Luxman 590ax integrated amplifier and need to borrow RCA cables.

I am concerned about having a fully balanced DAC running into a fully balanced amplifier and NOT take advantage of the two balanced units. My test should help me decide how to proceed.
georgehifi's avatar
georgehifi
10,312 posts
 
Hgeifman,even better with the Bricasti M1 DAC as it is even lower in output impedance than your Ayre at 40ohms output impedance!!.
It's all about "Ohm's and Kirchoffs laws"
Both are a perfect match with your Lux and will have better drive than most active preamps.

Cheers George
charles1dad's avatar
charles1dad
10,227 posts
 
Hgeifman,
What preamp do you plan to use? My understanding is that the Bricasti M1 has a preamp section/output that's likely to be of high quality. You'll need to choose a high quality active preamp for this comparison.
Charles,
georgehifi's avatar
georgehifi
10,312 posts
 

As far as XLR (balanced) or SE (single ended) goes.
Unless you plan to run 10's of meters of interconnect from the dac to the amp, single ended connection should sound better, as usually there are less electronics in the signal path.
Unfortunately many amps these days just have an added balanced opamp at the front end for XLR connection after which they go back to single ended, going single ended bypasses this opamp.
And the final connection to the speakers in almost most amps is single ended, just + signal, and - which is at ground potential.

Cheers George
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