What SET amp can drive the Von Schweikert VR1-89dB

Look at a low-powered,Class A SS amp. Tubed power amps are nice, but can be maintenance nightmare.

Depending upon your SPL needs, you could possibly get by with a 300B SET with about 8 watts. This would be marginal in my opinion. Probably most people would be happier with a little more power, like an 845 SET with about 20 watts. If you like the parallel feed SET amps, you could have a little wider selection.

the von schweikerts as a line prefer heftier push/pull designs.

The Vivas should work fine or possibly the Sophia Electric 845s/Princess rectifier.Happy hunting.

I would agree with Jrd351,with one caveat.VSA's speakers,though high in efficiency,represent a difficult load due to their complex crossovers.My former VR-6s ,at 96db,should be able to be driven by an SET amp.They didn't come to life until I used 600w/ch monoblocks.But the VR-1s are a two way monitor with a much less complex crossover.What effect VSA's "virtual reality {VR}" crossover will represent to the amplifier,is another question.I would advise you {Musiclover58} to borrow an set amp and compare for yourself.There is a large difference between a SET and a push-pull SET.Also between a transistor and tube rectified unit.
The Vivas are successfully driving the big Sound Labs and that should be a challenge for any amp,let-alone a 20-30 w/ch SET.You make the call.