bogdan_borko said:
Only a suggestion about supply of the signal part: circuit appear not to have much open loop gain for improving PSRR and this may lead to a circuit with good sound... and huge hum!
Rule of thinking,when design circuit with low overall feedbak, is that NFB not available (or not usable) for improving PSRR, must be used elsewhere (in stabilized power supply) or, otherwise, must be found some "trick" to improve PSRR in some way. The circuit, as is now, will lead at some delusion just because of poor PSRR. I've tried something of similar many years ago... with more traditional circuits and the result was very discomforting at hum side as, at high frequency side, was bright and good as a cream julep! Rethink supply and enjoy!
Ciao
Piercarlo
PS - Avoid the common mistake of improving PSRR only with "brute force" and tanks of electrolitycs: keep in mind the ESR which, at frequencies above a couple of KHz, is a more determinant factor for sound instead of "raw" tons of farads! Essentially, use electrolityc capacitors as *energy tanks* only, not as a filter devices because ESR, when frequencies go over some KHz, cut the capacitor into a raw noisy and non linear resistors wich can brutally enhance intermodulation across supply rails - and, faced to this problem, a low NFB circuit is in a very poor condition for defending itself and the signal which transit inside.