300 Watt Tube Monoblocks

@hiend2 

The ARC Ref 330m x2 is a great suggestion.  What speakers are you running?  Do you happen to have at least two, dedicated twenty amp services in your listening room?

Recommendation: don't.  (room heater, expensive to maintain)

Get a pair of Class A transistor amps. With the poor quality of modern power tubes, chasing failures in 16 or so tubes is a sure recipe for misery.

I am a fan of tube electronics, but, I don't like most high powered tube amps.  Most sound brittle and unpleasant as compared to lower powered tube amps AND as compared to good solid state amps.  If you must have that much power (I don't know of any speakers that truly need that kind of amps), look to solid state.  it will sound better at a MUCH lower price.  As yoyoyaya mentioned above, keeping a  whole lot of power tubes  running properly is an expensive proposition with a lot that can go wrong.  

How about the Audio Research Reference 330M or maybe the 750SEL if you're into overkill?