Unison Research Performance integrated amplifier

Not sure about the Performance but I had the Unison S6 before. Nice midrange and high but the bass a bit slow and light for me.

Splendid amp, don't worry about the bass: it offers plenty of it, it's more a matter if your speakers are good enough. Have owned it for three years now, Tungsol 6550 makes a fantastic match as for tubes.

I'm late to the party in terms on response, but I will add my 2 cents.  It's among the best tube amps I've ever heard.  If you pair them with Opera speakers (Sister company), then you're in for a treat.  

 

It's very very heavy.