Balanced Low Power Tube Monoblocks?

Not to long ago i was looking for amps along the same lines you are, I ended up buying the Manley Snappers. Might want to put them on your list.

Tvad those Audio Valve 60 watt monoblocks might work for you;I think they are a balanced design but not 100% sure;might be worth checking out.
I have the Challanger 180 monos and they are just fantastic
driving my soundlab M2's.
Auto bias circuit that lets you run el34's,6550's and kt88's ;you can even mix then up it you want but I have not tried that as of yet.
Presently using JJ kt88's with very nice results.

Tvad -sorry but I just noticed the 60 watt mono's are only RCA's;the challanger line is fully balanced but high power;sorry for the error.

I remembered years ago Avant Garde demo their big Trio in San Francisco Stereophile show with BAT 150SE and it was mighty impressive, in fact I voted that room as the best sound of the show. if you don't need that much power, 75SE will do fine and under your budget though it's not mono block.

Balanced ... Hummmm ... (scratching my chin). If you can live without balanced, I can suggest the VAC Renaissance 70/70 (Mk. III or Signature). I started with a 70/70, then ran the monoblock "140/140" version for six years, and now I'm back to the 70/70 (Mk. III) which I alternate with a darTZeel. The 70/70 is one chassis, but completely dual mono, all the way down to two power cords and two on/off switches. A very potent 65 watts per channel (excellent output transformers and power supplies). Real quality - $14k in 1999 dollars - unlike VAC's Phi products, the Renaissance amps are all point-to-point wired. The amp autobiases the 300B's and there's a tube shut-down feature which automatically kills power to any output tube that fails - it's a zero maintenance tube amp (there aren't many of those).

I run mine from a fully balanced preamp and a 25 ft. balanced interconnect with Neutrix XLR-to-RCA adapters - sounds super. I'm using Sylvania 6SN7 GTB chrome tops for drivers and phase splitters, and the original 300B's that came with the amp.

Most people don't know what these amps are - you can pick one up for $4k/$5k.