Tube Amp Recommendation

Calvin,

For your purpose, there are no better amps than the ones made by InnerSound to drive the type of capacitive/resistive nightmare that your Acoustats represent. It ain't tubes, but since you're using a tube preamp, it will almost sound like a tube amp. It will handle the load with ease and allow the Acoustats to open up and do their stuff. Most "tube" amps on the market won't even come close.

Although I'm not very experienced with tube equipment, I am aware that an OTL type amp may be the only tube-type design that can drive a load of that nature. The OTL designs use no output transformer, but instead have a cathode follower output tube so that they can drive lower-impedance loads with better stability & coupling. Joule Electra builds such a design; no doubt there are others as well.
Also refer to this thread "tube amp for a difficult load":
http://audiogo5.iserver.net/cgi-bin/fr.pl?aamps&1000150251&read&h24&zzlWellfed&&

Calvin,

I think you need to decide if you like Tubes or your existing speakers better. Because for $1500 used, you are not going to find a tube amp that can drive those speakers well. Especially when compared to a $1500 SS amp.

With more of a budget, I would suggest the ARC VT100 amp ($2500 or so used). This tube amp could drive the speakers pretty well.

Personally, in that price range, I would look at Monarchy solid state gear. The Monarchy SE100 Deluxes and the SE100 amps are great amps and sound a lot like tubes due to their Mosfet outputs.

or

A step up from Monarchy is Plinius SA100 mk3. This amp can be had used for $2200 (which is a virtual steal). Plinius is a world class amp that can only get better if you get two of them and go MONO.

Anyway, if you like tubes better than your speakers, I would suggest getting new speakers. If you like your speakers more, get a musical solid state amp like the Monarchy or Plinius gear, and I think you will be quite amazed.

This advice and a cup of coffee nets you a cup of coffee.

Peace.

Keith