I don't know the KT77 sound but it is highly regarded when compared to EL34's. Different manufacturers of 6550's and Kt88's can sound very different from each other. ex SED 6550 is very linear from top to bottom but not very detailed. Tung Sol 6550 black plates have that glorious midrange of the EL34 but with a lot more power. Much better base and only slightly better highs. EAT KT88's or original Tesla's (not JJ) are extremely detailed and very linear. The best if that is the sound you're after. Original Gec KT88's are very similar but a little dry sounding. SED KT88's are very nice and musical but a little bloated in the bass. Gold Lion re-issue has better and tighter bass than the SED.
Can't help with biasing. My Octave has Idiot lights that are designed for that amp.
Can't help with biasing. My Octave has Idiot lights that are designed for that amp.