oh WOW, it's my understanding that Mentor stack didnt have that dual 3-pin to 4-pin female cord in the box (iirc). Thats a great little addition to the kit as those are a bish to track down and have few quality options. .
It's an optional accessory, which costs extra that can be added to your order before checkout.
Both sides. Pcb on sockets by the green caps
Will shoot the question to Flux.Hard to say without drawing. But if i look at amp section of Mentor, this will be DC servo. Important part of the amp. Because one day your headphones can be damaged. And this nobody want. Some producers try to go other way. Non-feedback circuit. Even DC servo. Than you can listen some not friendly sound when you connect headphones to output. Producer come with recommendation like first connect to amp headphones, than turn on device. Or safety relay at output and DC voltage monitoring at output. There is many possibility. But only my speculation. Best will be ask Flux.
Google did find s
There's an interesting op-amp on each channel that is sand-off, not sure what it is for.
I'd think that's responsible for the power amp input stage. Looks to be a dual opamp, and I'm pretty sure I've seen that face before... if I had to place my bets I'd say that's an RC4580I. Used as poor man's fully differential opamp, I guess? (Would explain why what little distortion is there unloaded is domanent H3.) What follows must be inverting, as the capacitor as between pins 2 and 6, the inverting inputs. Either way, the opamp is clearly not the bottleneck, the output stage seems to have some current-related symmetry problems instead (distortion mechanisms #5-7 may be worth checking for).
I just read about.. 