Tube Amp for Green Mountain Audio Callisto

With requirements like that you could get by happily with a 3W 2A3 SET amp. You would lose a little bit in dynamics, though.

With an 8W 300B, you'd have plenty of dynamics. (SETs, with their class-A operation and frequently overbuilt power supplies, and ability to swing much higher voltage than their wattage rating suggests for brief periods, usually have excellent dynamics within their power capabilities.)

Roy's speakers are an extremely easy load and SET-friendly despite the moderate sensitivity rating.

Srosenberg,

95 dB peaks at that distance is a far different story than 80 dB - in fact, you need about 32 times the power! So, forget what I said about a 300B and definitely forget about the 2A3! :)

(I know you didn't indicate you were looking at SET specifically but I thought I'd throw that out there.)

IF you are interested in SET, an 845 or 805 design would still serve you well. Or, actually paralleled 300Bs for around 20W.

I've had three different pairs of GMA speakers including the Continuum 3. Six Pacs were great amps on them but an 845 SET was even better.

(The Pacs are the best push-pull amps I've heard; triode operation with 0 NFB is a great way to do P-P!)