This might be an absolutely ridiculous question, and make me sound like an idiot, but I feel in my gut the logic at least on paper isn’t ridiculous. I have my Zen DAC feeding my SP200- DAC set to variable, to use Bass X and the way better volume knob on the Zen. Anyway, because the SP200 is, at least to my understanding, “cleaner” than the one coming from the Zen, that it makes sense to have the volume on the Zen lower, and let the amp do most of the heavy lifting. Sort of like a garbage in garbage out, thing. Not that the Zen is garbage- I love it, but that if the amp, as low as the signal might be, is inferior to the THX that I’d want it involved as little impossible. I don’t know. Someone educate me, please.
Decrease the volume of the amp and the DAC decrease the performance of each one in terms of distortion and noise. If your purpose is to get the best performance in terms of distortion when you’re using the speaker you should max out the bass X and set the volume with the DAC and when you’re using the headphone max out the dac and set the volume with the sp200 with the gain at the minimum possible if you never max out the amp try to lower the gain. This is often the rule but in order to be sure at 100% you need specific measurements of all the devices involved
This is actually not a simple question, it depends on how good the Pots are in the various units, generally pots are less crap at higher levels.
However, It depends on what the volume control on the amp actually does, on a lot of headphone amps it just attenuated the input, or it’s immediately after a buffer with unit gain, in which case you want the pot as high as feasible, and to control volume with the better pot.
However there are other ways to use pots to attenuate volume, if it actually changes the amps gain (i have never seen this on a cheap amp), then the quality of the pot is less critical, and you want the amp running at the lowest gain you can.
Probably on the THX amp, given the crappy pot, you are best off with the amp at or close to maximum, and using the better pot, assuming it’s actually better.
But really the right answer is try both and pick the one you prefer.
This isn’t possible 'cause it means that also when the pot is at minimum you get an output. In order to implement something like that you need 2 pot one that works as attenuation of the input level and a second one that set the gain instead of a classic switch but I’ve never seen an amp with this kind of implementation.
It’s how PSAudio preamps work.
May be true with phono preamp but definitely not with an headphone amp or speaker amp
This
In most potentiometers, the middle of the pot has the best channel balance.
Like you said, in amps that use the potentiometer to attenuate from the input or after a buffer, running somewhere in the “good zone” of the poti is what I would recommend.
Yes it is very possible. Lots of mixing desks do it this way because it means you can have attenuation, unity and positive gain all in one fader/knob.
all mixing desk i know have a fader as attenuation and a pot for the gain