A correction. Audio Research does service the 100.2. Mine blew up about a year ago. Because of this thread, I thought I had a doorstop. On a whim, I contacted Audio Research. They are accepting the 100.2 for service. I had to wait about 3 months for my turn, the I was given an authorization to return. About a month and a half later it was on my doorstep.
The cost was very reasonable considering that many parts were changed. Including transistors, capacitors, and even some wiring that had melted by a previous tech during routine maintenance.
I finally got the opportunity to listen to the amp last weekend. It sounds better than I remember it, ever. I don’t know if there was any secret sauce applied, but at the very least, the 100.2 is up to full spec and operating like new.
The sound is rich in midrange sweetness and inner detail. There is plenty of detail and the soundstage is deep and wide. Dynamics are natural. Overall the sound is warm, without sounding overly colored or unnatural.
I spend all day listening to it, and forgot how loud it was. (My girlfriend came in to remind me :-). One thing that happened as I listened to both familiar and unfamiliar tracks was the lushness of the tonal color. I also noticed dynamics that grabbed me, but did not fatigue.
I would love to know who designed this amp, because it is honestly one of the most musical amps I have ever heard. I am very excited to have it back. It is a perfect match for my Joseph Audio Pulsars. My source was a Bryston BDA-1 and my preamp is currently a Bryston BP-20. Both excellent sleepers and great value recent vintage with a straight wire with gain sound.
I hesitate to say that this is the best I have ever heard, because there are many versions of excellent sounding and satisfying stereo gear. Even at different price points. Thanks to audiophile friends and music stores, I have heard some very impressive sound. That said, after forty or so years of chasing sound at different budget levels, this is a new high for me.
I think it’s time to find an excellent matching tube preamp.
A shout out to the American Icon of high end audio. Audio Research service of older products, along with the continual development of superior products deserves much praise.