tube amp will drive von schweikert VR4-jr?

I think these speakers like power. I've tried all sorts of amps and they always seem to come alive with more power. Tubes are great with them. They sounded terrific with the VTL 450 amps (tubes) and the Parasound JC-1 (solid state) both similar power, 400 watts. They sounded a little weak with the Pass Aleph 2s (100 watts) and the Linn Classik (70 watts) Tubes, yes, but I'd look for amps with at least 100 watts if it were me.

I'm running my JRs with a BAT VK60 for the moment and it is working out extremely well. No signs of compression or strain, even at moderately high volumes.

Being only moderately efficient, I think the speakers can benefit from being fed more power, but they do very well with less. They manage to make do with what you give them.

The Stereo Times reviewer used the Almarro A50125A with the VR4s, can give it a try.

I run mine with Quicksilver M80 tube monoblocks (80 watts per) and they sound great. They don't seem to be lacking in power at all with the VR4-jr. I recommend looking into the Quicksilver V4 tube monoblocks (conservatively rated at 120 watts per). I would love to here that combination and at some point plan on it!