Leonard is no longer at Audio Research. If the bass is a bit lacking, I would suggest your output tubes need to be replaced. I always tell customers if your buying a used tube amp don't expect the seller to re-tube it. My guess is your output tubes have come to the end of their life. You might also wish to talk to an authorized ARC service provider in your area so he can have a look at your amp to make sure it's functioning properly. I think the MK3 version of that amp is quite good. They normally don't have bass impact issues. BTW the proper setting is 65mV and I believe it says it on the circuit board right next to the resistor your supposed to measure across.
ARC vt100mkiii Questions?
I brought one of these 2ndhand lately. The amp had both side boards inside replaced and only the transformers were old. So, it is not broken in. Well, I would like to get advice from other owners about its bass responds. It seems on some music esp. acoustic double bass, the bass is a bit soft and undefined but on others like big symphonies, it sounds quite right with good dynamics. But overall, the bass is not as tight as I would thought it is. I use JBL4425 and Haarbeths HL_5S so to think it is not the speaker’s faults. Does yours have very tight bass? What bias settings were yours set to, mine is set to 60. Thanks.