Jude sent me these photos of his Pico Power that he's planning to use for a guide, so I'm sharing them here:
I have waited a long time to post this but I can no longer hide my conclusion that there really is a difference in the sound between the different gain settings. It is almost as if (or may actually be that) the Pico Power is delivering more power in high gain mode. My Heaven VI is very sensitive to power, ramping up in the bass and mids as power increases. It is one of the reasons that I love the Pico Power so much with it. I am finding that I get more prominent bass with noticeably increased mid-bass slam on high gain by comparison with low gain. (I am not sure what to make of mid gain; I am actually not sure why this setting even exists.)
I thought that it might be placebo but listening today to Janis Joplin's Greatest Hits, the difference was impossible to ignore. (I was doing careful channel matching as much as possible when switching back and forth.)
The volume pot on my Pico Slim has excellent channel tracking right down to the bottom and I am using it on high gain now with IEMs. I don't get a lot of play adjusting volume - low gain is better for that - but with the stiff but still smooth volume control, it is fine.
To be sure the Pico Power sounds just great on low gain. But for that little extra bass pop with the Heaven VI, it is high gain for me.
With other headphones it may not be as noticeable. (I do feel that it is still there with Flat4 Kaede but it is less obvious.) I wonder if others have experienced the same thing?
I don't have the Pico Power (yet), but if we are talking about the same thing, I noticed this with the gain switches on all my devices when using my NT6 Pros which eats any power it can get. However, with my less power hungry headphones it is less noticeable. The devices I use with a gain switch include the BH2 an the DX50. My guess is that it takes more power to drive the lower frequencies so the extra power is just more noticeable there.
I just ordered a black Pico Power. I can't wait to get it. It will probably get to me before my JH Audio JH5 Pros come in the mail. I guess I'll just use my crappy beats by dre studios in the meantime while I wait for my JH5's.