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
The Nuprime Dac-10 might be nice. I say this because I'm using the phenomenal IDA-16 integrated and LOVE it, not because of the new review out in Absolute Sound that my buddy told me about. I haven't read it as I've stopped getting the audio rags years ago. They're all rubbish.
All: I want to thank everyone above for your comments and suggestions. They were helpful and appreciated.

Philip from On Higher Note (Luxman Distributor) said "To truly separate the preamp stage from the L-590ax, you need to run an RCA cable into MAIN IN and then hit the SEPARATE switch. If you run balanced cables, you will also be using the preamp stage of the L-590ax”.

He had no comments if the 590ax is, or is not, a fully balanced amplifier. If we have to use the RCA main in jacks on the 590ax, it seems we are not taking advantage of the two balanced units (DAC and amp). I was told that, if RCA plugs separate the pre-amp section from the power amp, my Luxman 590ax is really not "fully balanced". I do not know or understand. The 590ax sounds great so maybe it probably is not important. Any comments on this?

My loaner Bricasti M1 DAC with volume control is due next week. My plan is:

1) Plug the Bricasti M1 DAC using balanced XLR cables into the balanced inputs on the 590ax. This means the 590ax is operating an integrated amplifier including its pre-amplifier. The Bricasti M1 will only operate as a DAC.

2) Plug the Bricasti M1 DAC using RCA cables into the RCA main in jacks on the 590ax and press the separate button on the front panel. I will turn the input selector to another setting but I do not know what setting yet (any suggestions?). This might not be important since the separate switch is on. The volume control will be done using the Bricasti M1 DAC and not the volume control on the 590ax.

The above cable wiring and operation will enable me to easily switch between integrated amplifier operation and the Bricasti M1 DAC used as a pre-amplifier (and its volume control).

It is going to be an interesting experiment. I received many different opinions for running the DAC directly vs. through the preamp section of the Luxman. Obviously, it is a very gray area and I need to try it both ways in my system. Thanks again.
"I've seen it all too many times. A typical example of this is my cd player which has both single ended and balanced outputs, the extra opamp they used for the balanced had gain compared to the single ended output, which bypasses the balanced opamp, therefore one less opamp in the signal path from the single ended output."

So, basically what you're saying, is that a manufacturer may raise the gain on a single ended components xlr outputs to make it appear balanced if someone were to look at the spec sheet? I never even considered something like that. My ex-girlfriend from Russia wasn't even that unethical.
08-20-15: Hgeifman
My plan is:

1) Plug the Bricasti M1 DAC using balanced XLR cables into the balanced inputs on the 590ax. This means the 590ax is operating an integrated amplifier including its pre-amplifier. The Bricasti M1 will only operate as a DAC.

2) Plug the Bricasti M1 DAC using RCA cables into the RCA main in jacks on the 590ax and press the separate button on the front panel. I will turn the input selector to another setting but I do not know what setting yet (any suggestions?). This might not be important since the separate switch is on. The volume control will be done using the Bricasti M1 DAC and not the volume control on the 590ax.

The above cable wiring and operation will enable me to easily switch between integrated amplifier operation and the Bricasti M1 DAC used as a pre-amplifier (and its volume control).
Presumably selecting "separate" mode disconnects the preamp section of the integrated from the power amp section, and I would guess (and hope) that deselecting "separate" disconnects the "main in" jacks from the power amp section. However even if all of that is the case, if both inputs are connected to the Bricasti simultaneously it is possible that some low level leakage of the signals coming in on the input that is not selected could find its way to the power amp section, with audible consequences.

Therefore if you want to have both connections in place at the same time what I would suggest is that you first connect each of them individually, and verify that with the other one selected (but not connected) that you don't hear anything, or at least that you hear very little. If you do hear something when main in is selected but not connected, changing the input selection to something other than the balanced input that is being used may help.

Of course, only change connections while the amp is turned off.

Also, you may want to make use of the level adjust set screws on the rear of the Bricasti, which control the level of its balanced outputs only, to equalize the volume levels in the comparison.

Finally, I'll mention that fortunately the Bricasti drives its unbalanced and balanced outputs from separate and independent driver stages, according to its manual. With a lot of other designs, in which that is not the case, the results of your comparison might be muddled or altered if both outputs were connected at once.

Good luck. Regards,
-- Al