Recommendation for higher power tube amp

Wow, great responses, here's what I am thinking.

Different speakers - I have considered this as a next step, and was thinking about Zu, Devore 3XLs, and Joseph Audio RM-25si, all of which I think would get my amp closer to the loafing so enjoyed by wolf_garcia's Carys.  Any others I should think about?  Maybe start another thread...

atmasphere, thanks for the math/design explanation, conceptually I knew this but the details are VERY illuminating.

erik_squires and testpilot, I would love to end up with combo of tube pre and ss or d power, but that's too far of a $$$ leap right now. I have also considered a Schitt Freya through a Krell 305il, an integrated that I don't use as I very much prefer the BAT with the Thiels.  Low cost, low risk, plus I could finally try a BAT/Schitt system.

I am very much intrigued by the ideas of building a kit amp, but imagine I would need to tune up (learn?) some soldering skills and have some time set aside to do this, but if I did, I imagine I would go down the 300B route, as I was inspired by Herb's recent review of the EleKit, which in turn gets me back to high efficiency speakers.  Eventually I do want to hear what the fuss is about with 300Bs.  But I will look into the VTA.  Bonus here is that if I built an amp from a kit, I'd have the confidence to rebuild the xovers on the Thiels!

And fyi, Underwood's recent offering of a Music Reference RM-200 mk2 (and Fremer's review, and my hunch that the current capabilities of the VK-55 are what makes it sound good with the Thiel's to begin with) is what got this ball rolling.

Thanks all - cheers and enjoy the music!

OK, my takeaways are - 
1) Get different speakers (currently favoring the Devore 3XLs based solely on web based research) or
2) Go tube pre and very high power amp or
3) Try a Music Reference RM-200, no holding my breath for sonic epiphany (and also being wary of falling boulders, while Persephone (my wife?!?) looks on from the kitchen).

mikapen - I would love to find that dealer w/ amps I could demo at home, but living two hours from civilization makes this tough.  I did actually find a dealer in the big city who just happened to have the 2.3s sitting around, let me try several amps with them, which is how I started down the tube amp road in the first place.    

Great discussion and insights, this has helped me make informed choices, plus entertaining as always, thanks all.

I have thought about using a sub fed from pre-pro, that could be another potential path, any recommendations?  Is it worth it to go the whole enchillada room correction route with something like the DSPeaker anti-mode 2.0 or similar,or is any preamp with dual outputs ok (already have a sub).

Yeah and the more I think about it, if adding power is not going to significantly change SQ, why would offloading the bass to a sub do much either?

OP check in - gave up (or put on hold) this idea for developing the system, instead worked on the room and some other tweaking.  But 2020 might be the year I look for the next speaker, based on listening I am considering Quads and based on reading Devore as potentially good choices.  But I also might mod the crossover on the 2.3s first.