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!

I ran my Thiel 2.4s with a VAC PA 100/100 that I had factory upgraded to the same front end as the phi 200 VAC. Has a 2 ohm and 4 ohm speaker tap. I would look to spend a little more if you want the iron (transformers) to handle your speakers. A used VAC phi200 could be on your list with a stretch. 

Years ago I owned the Pass X250 amp w/the power meter on the front and borrowed a pair of 2.3's from my local shop they had for sale used and it was amazing how they buried the needle on the power output needle on the faceplate ie took a huge amount of grunt to power them.  After that I owned (unfortunately:) a new pair of 2.4's that weren't quite as tough the load on the Pass speedo that the 2.3's were.  I'd go for the RM200 if you're stuck on the 2.3's.  If you're gonna do tube amps get some speakers that will do them justice.  cheers & have fun

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...

Watch the impedance. If you want the best performance out of a tube amp, the impedance best not be under 8 ohms especially in the bass.

Sorry, but why You need 50-100 W, that You never use, and pay too much money?....Better variant is - speakers with 94 and more sensitivity and quality SE with 4-8 W /that is better than PP with sharp and metal sounding, caused by switching signal between first and second shoulders of PP construction/.