I believe what SET amps do is retain the inherent harmonics of the music better than any other topology of amplification. It's difficult for me to reduce to writing, but the 'noise' an SET makes sounds more like MUSIC than thru any other kind of amp.
If you Search for somehting like 'SET sound' on the SET Anylum, http://www.audioasylum.com/scripts/tv.pl?forum=set , probably you'll learn a lot.
If the VAC 30/30 is a 30WPC amp, you'll find many SETs with enough power including the great-sounding Antique Sound Lab AQ1006, an 845-based monoamp rated at c. 25 Watts in 40, 8, or 16 Ohms; http://www.divertech.com/asl1006845dt.html .
BTW, the common triodes used as output tubes in SETs and the typical power output is--#45, about 1 Watt; 2A3, about 3 Watts; 300B c. 8 Watts; 211 c. 15 Watts; 845 c. 25 Watts; and 805 about 50 Watts.
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