Positive Feedback is all over unusual tube gear and here are two reviews of amps from companies deep in the audio underground. First up is the $2k Piano integrated from Jasmine Audio. 34 watts per side, two reviewers at PFO like what this amp dishes out and offer lots of reviews in comparison. Nothing terribly out-of-this-world great but "audition worthy," as they say.

Also up is a tube hybrid amp from Germany's AcousticPlan. Recently gaining in popularity, these hybrid integrated amps normally use tubes for the preamp section and solid state for the actual juice. Here, AcousticPlan's Santos is a pure amp with both tube and SS circuitry in an unusual design that the reviewer breaks down in an informative article complete with heaps of praise. Nothing is ever cheap, of course: 5200 euros for the amp. AcousticPlan also has companion preamps and integrateds as well as a couple speakers.

AcousticPlan Santos Review

Jasmine Piano Review
Jasmine Audio
AcousticPlan