And loving it! Only one initial build issue- reheated a few contacts and "crackling" gone. Had no issues with resistance or voltage checks.
Here's what I've done since initial build- really not that much
1- padded down the volume a bit
2- NOS tubes- Mullard and Tung Sol
3- By passed audio caps with Teflon caps
I'm enjoying this so much (using HD 600's with Cardas cable) that 1- I listen via headphones sometimes just because I want to, not because I have to; 2- no desire to implement the Speedball (ie- when it works don't fix it).
Maybe one day I'll pick up and install an Alps Blue Velvet, but then again, the volume control is working splendidly since I soldered in 4 resistors-
Crack/Speedball, SEX 2.1/C4S, Bryston BHA-1
Sennheiser HD600/Cardas cable, Beyerdynamic T1 2nd Gen, Hifimam HE560/Hifiman balanced cable