Quandary

I think that the $300 review, which involves two trips by the dealer, plus the opportunity to have the $300 put toward the purchase price is a reasonable offer.  Whatever you decide, it is a decision informed by much more than most people base their decision on--you got to hear the amp in your own system, at your leisure.  

Yes, tube linestages can work well and sound good with solid state amps.  But, the biggest difference in sound comes from using a good tube amp.  I hang out at a very serious audio shop that does not sell ANY solid state amplification.  They also don’t sell high powered tube amps.  So many visitors to the shop are utterly amazed at the sound; for some, it is like a religious experience.  They have never heard this kind of sound at shops pushing solid state and high power tube amps.
 

It is all about the sound.  As good as a hybrid tube/solid state sounds, I don’t think one gets close to the full measure of tube sound without a tube amp.  I’ve used solid state linestages with tube amps, and I prefer that combination to tube linestage feeding solid state.

Tube gear, in particular power amplifiers, vary much more in their sound than do solid state amps.  It is not easy to characterize tube amp sound and know tube amp ‘sound” from just a few examples—Audio Research sounds radically different from Audio Note.  Also tube amps require much more care in matching requirements of the speakers.  In that sense, good solid state is “safer” in terms of avoiding incompatibility.  I find Pass Labs to be decent solid state stuff; although much more particular in terms of speaker matching, Pass Labs’ other brand-First Watt—is even better sounding to me.