I like my Heathkit AA-30 which is an early version of the AA-111 with only cosmetic changes. This amp has good bass response and a very pleasing sound. The OPT are Chicago 51-29 which have a reputation for good sound. This amp uses a GZ34 rectifier which I think is part of the reason it sounds so good. The only mods I made to mine was to change the leaky coupling caps to 715 orange drops and change the cathode bias resistor for correct bias. The downside of this amp is that it uses 7199 drivers which are scarce and expensive. Also the pcbs are very fragile and hard to work on.
I have a rebuilt ST-35 which I like but Heathkit has a much fuller sound. I have also heard good things about the Pilot SA-232 which also uses the GZ34 rectifier. I plan to build a pair of monoblocks based on the pilot circuit.
