DAC Direct to Power Amp or "Buffer"?


I recently returned to the DEQX solution for room correction via PreMate+. While it rendered an excellent DAC redundant the DEQX DAC is quite stout, and the room correction improvement is well worth the change. Of course, the PreMate+ has a volume control and is intended to also replace my preamp.

I much prefer the sound quality if I keep my analog active preamp in the signal chain between DEQX and a Pass Labs 30.8 amp. My preamp has transformer coupled differential balanced topology, and I suspect the transformer "buffering" of the DEQX output may be responsible for what I am hearing. The Empirical Audio "Final Drive" units seem to have been designed with this in mind.

I know conventional practice is to go DAC direct to power amp if the DAC has a volume control, but the improvement I hear with my preamp kept in the signal chain is far from subtle.

Has anyone had a similar experience to mine? Any "Final Drive " users out there?
jb0194
The Deqx output stage will drive any poweramp better than any TVC passive can.
 Also your old dac may have been a better dac than the Deqx. What your maybe liking is a bit of colouration that the TVC passive is bringing to the party, which they all seem to have, that's a bit of a bandaid fix for the dac differences?

Also read this, if your not using the Deqx volume control, above 70% of full. 
https://forum.audiogon.com/discussions/volume-control-question/post?postid=1445143#1445143

Cheers George
Based on my experience, I agree that setting the volume In the DAC to fixed (100%) and controlling the volume in the analog domain using the preamp will result in the best possible sound quality.

Any volume control adjustments made in the digital device will result in bit reduction reducing the sound quality.  I recommend the digital setting be set for the maximum and that you control the volume using the preamp. 
Just a thought, but have you tried connecting the DEQX to the XA30.8 via their unbalanced interfaces?

I realize that in general it is preferable to use the balanced inputs of the fully balanced XA30.8. But while I’ve never used the balanced outputs of my DEQX HDP-5 (I connect its unbalanced outputs directly to my power amp, with excellent results), I know of another member who was slightly dissatisfied with the sonics of his PreMate (not the PreMate+), which he was using via its balanced outputs in conjunction with balanced ARC equipment. So I would not rule out the possibility that your PreMate+ might sound better via its unbalanced outputs.

Good luck. Regards,
-- Al

Thanks to all!

One issue I did have running "DEQX direct" relates to my preferred modest listening volumes. The DEQX digital volume control would often sit at about 50% of full. With my preamp upstream I can set its volume controls such that the downstream DEQX volume control always sits above 80%, and I can use the DEQX remote to fine tune volume for differences among albums from the listening chair. I suppose using the DEQX unbalanced analog outputs direct to amp would drop output by 6dB, but I'd have to buy a pair of single-ended interconnects to try that option. For now I'm happy with the trade offs of keeping the analog preamp in the chain.
The DEQX digital volume control would often sit at about 50% of full.
This proves you have enough gain, but at 50% you are "bit stripping".
Your best to just have a passive pre to lower the output, rather than another active pre with even more gain again, if you do this the sound will be better.

Your The Empirical Audio "Final Drive" is just a unity gain or +6db gain buffer and will not lower the volume, so you can use the Deqx at 70% or higher.

My first pick for your situation is this for $49 this will do the job nicely
http://www.schiit.com/products/sys

Or for balanced you can use this for $699 in passive mode, active tube, or active solid state.
http://www.schiit.com/products/freya


Cheers George
Hi,

We have tested 72 digital front ends and in general a separate preamplifier does result in better sound. We did find a couple of dacs that had great sounding analogue preamplifier sections that compared with our reference $10000 preamplifier. The main problem is you need to find a great sounding dac first that sounds analogue and than that dac needs to have a separate great sounding analogue preamplifier built in, versus a digital preamplifier built in.

If the dac has a digital preamplifier than it is true that you should pin the preamplifier to 100% and not really use the volume control of that preamplifier section but if the preamplifier section is analogue and separate from the digital section than you might have a great pre section based on the quality of the preamplifier section in that particular dac.

This is really noticeable when playing DSD audio.

Cheers and just my opinion.
Recently, I bought Oppo Sonica DAC which has volume control. It sounds a whole lot better going through preamp than directly to amp. For money, it is a remarkable DAC if you bypass the volume control.
thanks,

Based on my limited experimentation, I think the effects of impedance matching between the two options of with or without preamp in the chain is equally important. This is regarding the difference between the preamp output impedance as compared to the impedance of the DAC with a volume control.
I think it's very much dependent on a lot of things. My Mytek Brooklyn sounds phenomenal when directly connected, but I still use a Parasound P7 in the middle because I also do movies.

If Mytek did a multi-channel DAC/pre I'd be all over it.

Best,

E