Dual volume control - it should be standard

If someone says yes, there will always be those who will say no or it depends. However, it appears that people who are not too lazy and have good hearing say yes in this case. By the way, Redgum has now an option of single volume control, but they warn on their website that it will sound a little worse.
Also, moving the listening position left or right will not always help and can actually cause even more soundstage distortion. Depends on room and recording, I experimented with the amp I had before with single control.
The point is that there is no way around. At least none that I can see.

I now sit perfectly still so as not to distort the soundstage. In fact, I've found that if I sit on spikes directly from my butt into a hard wooden chair, although extremely painful, helps curb the resonance my body creates from my heartbeat, breathing, sighing at the beauty of reproduced music, and otherwise non audiophile writhing around. The used medical head brace I found in a hospital dumpster also works wonders in keeping the imaging stable...that Mahler string section seems glued in place now...

Well, it is good know you are committed!

Committed is an understatement. Totally dedicated and profoundly submissive.

I can certainly understand the appeal from an engineering point (no stereo pot tracks perfectly throughout its range unless it's a stepped attenuator w/ individual resistors carefully matched), but I have too much OCD to keep leaving the sweet spot chair to walk up to the preamp and tweak the dials hoping the soundstage and centerfill are fine once I return...I'd never get any listening done!