Trying to understand optimal method of volume control with separates


I recently got a vtv eval-1 stereo amp to go with a topping d90/a90 dac/amp stack which is intended originally for headphones but doubles as a dac/preamp going out to the eval-1.  The d90 dac has volume control with a remote which is great for relaxing on the couch since the a90 amp/preamp only has a knob you can turn by hand but no remote.  I could be imagining things or recovering from an un-diagnosed ear infection but I could almost swear it sounds better having the dac at 100% volume or alternately having the volume knob on the preamp turned up higher with the dac lower.  Is there some optimal combo of preamp voltage and dac volume that fills in the music better somehow? 

I assumed that one multiplies the other and the only thing that matters is the total that comes out into the speaker amp but for some reason it sounds more full/even the other way.  The only problem is when I have the dac at 100% there's almost no room to adjust the volume knob without getting way too loud.  Having the preamp volume knob permanently up higher and setting the dac lower also seems to do the trick but I'm curious if I'm just insane or if there's something to it.
brandini
Just remember that those and most volume controls are merely attenuaters.. Only youd ears can determine which of yours sounds better
Be careful.
try to stay below 12oclock If possible.
my one preamp has a DB setting of +8, so if I use this, I stay off the volume a bit, if I hear any Jumble of music,  I don’t push it, speakers only rated at I think 250W peak. So I keep the volume and my ears sober.    Some music is played louder, acoustic, etc.  

  stay attentive to the volume!
Up until yesterday I was keeping the preamp volume at 12 oclock on medium gain and controlling volume with the dac. Sometimes it seemed like it was out of tune or out of balance and not that great sounding at higher volume. If I put it around 2 o clock medium gain but turn down the dac it sounds more normal somehow. Weird.


brandini
The d90 dac has volume control


This if it’s digital domain vc, should be used at or above 75% it’s full output, as not to run the risk of bit striping. So the ideal would be to set your preamp where you use the dac’s vc at or above 75% of full, this will give the highest resolution from the dac, below this can bit strip and reduce resolution.
What Wadia did with their flagship dacs was to have a owner gain settable analog output stage so you can use the digital domain vc near full for the best sound going direct into the poweramp/s, and forget about preamps.
https://ibb.co/sbW8QjC

Cheers George
It took many decades of testing on many different systems with uncounted different components but it was worth it to eventually determine conclusively the most optimal method is clockwise louder, counter-clockwise less loud.
Thank you so much millercarbon I didn't know those knobs did anything.  I turned them and the sound got louder! 
Thank gosh for MC.   
Now you at least know which way to turn them.
Paint some little arrows on them.
Post removed 
@MC  
  I tried that with a rocker type, and nothing happened.

With rocker type remember, "These go to eleven."

https://youtu.be/4xgx4k83zzc?t=39
Run your dac at 75% or greater. Use your preamp to adjust the volume for the most part. Analog volume controls are more linear and balanced above 50%. IF you had a separate power amp with a volume control, I would run it 75% to 100% and not change it. Enjoy the music! 
For the moment it seems that keeping the pre at 2pm medium gain and lowering the dac a bit works pretty well but I'm thinking about picking up a freya+ so I can finally do it right and have a remote.  Hopefully the gain won't be out of control but I can return it if it doesn't work out.
I’m thinking about picking up a freya+ so I can finally do it right and have a remote. Hopefully the gain won’t be out of control but I can return it if it doesn’t work out.
Get a $49 Schiit Sys passive as well, as I said the higher the dacs volume is above 75% of full the less chance you are "bit stripping" and lowering the resolution.
As you can send either back, and my bets on the Freya+ going back and keeping the Sys for the best sound.

Cheers George
brandini OP


Actually I forgot you can also use the the Freya+ in passive mode so forget what I said about getting the Sys.

Cheers George
Dan D'Agostino spoke to our group two years back and explained
that the DAC volume must be set at 60-80% of max otherwise
SQ is sacrificed. Sorry I do not recall the specifics as to why.