What volume level should a DAC be set to when feeding your Pre Amp


G'day All

I have an Accuphase DAC (DC-901) with a digital volume control that feeds my Pre Amp/Accuphase integrated Amp.  The DAC is fed via USB. It reports its volume level in db and altering the volume on the DAC impacts the volume level coming out of my Integrated.  I currently have the DAC set at 0.0db. This DAC level is purely a guess on my part not really understanding the technicalities of it all.  I'd like to understand better the implications of this DAC volume setting on my overall listening experience and whether or not the setting I have in place currently is correct.

Any advice appreciated.

Cheers
plb02
I remember a Paul McGowen (PS Audio) YouTube video where he says (paraphrasing Paul) "Adjust the output of your DAC/CD player so you preamp volume control is in the 12:00 - 3:00 position". He said "In the old days, digital volume controls had problems sending an accurate signal but now, that has been worked out and it's O.K. to adjust the DAC volume.". I tried to find the video but could not. The bottom line is your preamp's volume control sounds best in the 12-3 range. I've been doing this recently and find that it does sound somewhat better. 
Thanks @dweller, much appreciated.
What volume level should a DAC be set to when feeding your Pre Amp
I have an Accuphase DAC (DC-901) with a digital volume control that feeds my Pre Amp/Accuphase integrated Amp.

Dacs volume up close to full, or you can run the risk of "bit stripping" if too low (below 75%), an can cause resolution reduction 14bit 12bit and so on the lower you go.

If then with the dacs volume up close to full, if you are below 10am on your preamp volume because it’s too loud, then think about a passive preamp or active preamp little or unity gain.


Quote from Nelson Pass

Nelson Pass,

"We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.

Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.

Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.

What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.

And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp."


Cheers George
Thank you George.

I had "randomly" picked -15db on the DAC (its range is -80db -through 0db.  The only reason being this resulted in my Integrated sitting between 9 and 11 oclock on the volume control for regular listening levels.  I may have blindly determined the correct setting with any rhyme or reason. I have tried 0db on the DAC (full volume) and had no discerning change in sound quality (my ears are not that young). I also wasnt keen un running the volume way up to between 12 and 3 oclock for low level listening when the DAC was set to lower levels. I may be mistaken but figured this was working the Amp harder.

Cheers
I may be mistaken but figured this was working the Amp harder.
No the same, just letting the same amount of input signal through the volume pot to the power amp section, instead of shunting it to ground when the dac's vc is higher.

Cheers George 
0dB FS (full scale) should correspond to 24dBu.  Since 24dBu is a level related to 0.775V (1mW over 600ohm) it will correspond to 12.3Vrms.  When you selected -15dB your DAC would output  24dBu-15dB=9dBu = 2.2Vrms.  I'm not sure what nominal level should be.  I looked at one of the power amps that outputs 125W at 8ohm and has gain of 26dB.  That would imply 1.6Vrms input.  My current power amp Benchmark AHB2 has high gain position of 8.2dBu=2Vrms.  You should be OK.  My previous DAC had jumper selections of 0dB, -10dB and -20dB.  The best position for driving power amp direct was -10dB. 

You might find this useful:
https://www.av-iq.com/avcat/images/documents/pdfs/measdigaudlvls.pdf 
plb02 OP

It seems like your on a winner, it looks from other posts you have the Accuphase E470 integrated, it has poweramp inputs at 1.5v in for full wattage output on the back so you can forget about the preamp section, for the best most transparent/dynamic sound I would feed your dacs output which has up to 2.5v output direct into these poweramp inputs and just use the dac’s volume control.

Cheers George
Many thanks to all who responded.  A special thank you to the ever helpful Georgehifi.  I'll have a listen to the DAC to Power (bypassing the E-470's pre) and see what this turns up.

Cheers

Paul
I’ll have a listen to the DAC to Power (bypassing the E-470’s pre) and see what this turns up.
I’m sure you’ll be surprised, it’s a better even more transparent/dynamic configuration that what Nelson Pass said above that I posted.

Cheers George