Audio Research Corporation ARC Reference 600

I have owned many ARC and the Reference 300 is their best! The problem with ARC is that once aged, the circuit board will short circuit and BANG!*"|@# ... total up needed!

Let me also add that since you have speakers that have a 102dB sensitivity @ 1W 1 meter, noise becomes more of an issue. The Ref75 should be quiet enough, but what kind of preamp are you using? The s/n ratio of some tube preamps would be low enough to cause a definite backround hiss through your speakers which you may find objectionable. This noise can interfere with imaging, front to back depth, and low level detail. Just thought I would throw that in.

Another vote for the Ref 75's. They make the finest sound I have heard in my system. Detailed and dynamic, with good base slam, but no edge or harshness at all. They do not run hot at all. I am using them with sensitive Daedalus speakers and I have neighbors, so don't play at 100DB. I haven't been able to move the meters more than a micron, since I bought the amp. A proverbial no brainer if your speaker and music choice allow

You can get the same "hot rod" effect with a set of Ref 300s with half the cost and effort. Even the half power of the 300s is more than needed as others have already stated, but that doesn't seem to be your goal. I would have ARC go over the amps regardless of tube age. Just like a high performance engine these amps need an open check book to give their best and avoid costly repairs.

For the vintage, Ref 300 is superior in sound quality to Ref 600. Google for reviews and probably why Ref 300 are more $$ than Ref 600 in used market.