NAD 916 DC offset correction ?

Greetings to this distinguished international community from the UK ! Haven't been here for a while but hope some kind person will help.

Looking to improve on my pristine and unmodded A&R A60, and to bi-amp, I bought a NAD 1155 pre-amp and a NAD 916 6-channel power amp from the usual auction site. The 916 contains three bridgeable stereo power amps, so I figure one pair for tweeters and a bridged pair, ~90W mono, for each bass/mid driver :D

Both pre- and power work and already partially achieve the desired result, but the power amp has DC offsets of 35-70 mV, mostly negative FWIW, so I guess needs some work.

I've reset the idle voltages (currents) without results, as expected. The three mains transformers buzz a bit. I can't see any obviously faulty components.

IIUC the DC offset is governed by an emitter resistor, NAD having not thoughtfully provided a pot as they have for the idle currents, but I hesitate to infer which one from a post on another forum about a different amp ! If all else fails I'll try though.

I have the service manual, but that doesn't help apart from providing circuit diagrams etc, so if someone would tell me which resistors to replace with pots I'd be delighted.

BTW bi-wiring is worthwhile - try it :cool:

Many TIA
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