With all the excellent Class D amps available that can drive these speakers with ease, I'm curious why you are playing around with tubes.
If you like the sound produced by a particular tube amp, fine, but that means you are looking for something that suits your preferences rather than something that's objectively good. Also, the interactions between speakers' reactive loads with tube amps aren't easily predictable.
"Playing around with tubes" wrongly assumes that all tube amp designs will sound the same. They often won't, be they push-pull Class AB, single-ended Class A, have 300B, 845 or other tubes output stages-or any of numerous input and driver stage tubes. https://www.diyaudio.com/community/threads/input-tubes-for-300b.158499/
Solid state Class A amp designers have suggested that if such tube amps exhibit substantially higher distortion levels than other (Class AB, A, D) amps and yet are often aurally more pleasing to countless listeners than it may be due not only to percentages differences of the kinds of distortion those tubes tend to generate but also the amount of and how corrective feedback is applied, power supply decoupling techniques, the quality and minimizing the number of passive components and other factors which designers of expensive tube and solid state amps may be more apt to optimize.
As for subjective reactions to speakers and amps, there are countless ears at many forums, including this one, who've heard way more hardware than I'll ever hear. And many, if not most of them, often can't help but point out differences between the sound of speakers, amps and other hardware, even after controlling for obvious variables. Case in point: Some at this thread note what they found strong sonic differences between the tweeters in the Revel 226/228be tweeter and those in one or more Harbeth speakers. https://forum.audiogon.com/discussions/revel-performa-f228-be-speaker-thoughts
Naturally, I would have to audition at least one Harbeth model vs. one these Revels to decide for myself whether those "harsh", "cold/analytical" or unpleasantly "revealing" claims about these Revel beryllium tweeters are evident to my ears and playing my source material. However, if they mostly are true, but if I end up being otherwise thrilled with what I hear from the Revel's tweeters, midrange, imaging and soundstage (and maybe price too), what might make the berylliums sound as nice as the Harbeths likely do?
Unless some amplifier X, (which I might never find) along with properly loading the Revels, has some special way with the tweeters to make even Harbeth speaker lovers swoon, bi-amping has long proved to be the best sounding way of driving almost any speaker system. In a three way speaker system, biamping (or still better performing triamping) eliminates almost all frequency response interactions and all distortions otherwise extant with passive crossovers. Thus, in this case, the Revels' midbass/woofers could be electronically crossed (or optionally with the passive network) and driven by an appropriately muscular Class AB (or perhaps Class D) amp. And the tweeter/midrange electronically crossed and driven with a 300 SET, J2 or other low power Class A power amp tube or solid state amp. With the correctly calculated changes for impedance matching there will be very little if any audible interactions with the any of those amps and the midrange driver, and likely far less with the tweeters. And I'm betting that most
ears would find those
tweeters sounding sweeter with those amps vs. most Class D amp designs.
Yes, this is really a question for a different forum. Nobody here is going to suggest using a 300B or First Watt amp in any circumstances where you care about measured performance.
If you want to use one of those amps for some reason, it's going to be for non-audio reasons. Which is OK if that's what you're looking for, but in that case you don't need external validation.
First, I had no idea that there existed a forum with an apparent "bias"
towards Class D amps. But they certainly are no more popular among audiophiles than another amplifier designs. As for measured performance, as explained, electronic crossovers, properly implemented, result in very low measured levels of distortion and other audible anomalies. Just ask powered Genelec and Neuman users here, of which there are plenty, and who seem endlessly pleased with the sound.
Likewise, well designed tube amp typically measure great and sound superb, however unfortunately super expensive those amps AND replacement tubes-especially 300Bs-often are. First Watt amps likely measure even better, and no tubes to replace. Yes, Class A amps are inefficient and get can very warm. But my listening sessions don’t typically extend much beyond two hours straight, after which I would power it off, so the trade offs would be good for the one small Class A amp that I’d be using for bi-amping the tweets/mids.
What was evident to me at this forum is that Revel speakers seem popular. And far from seeking any approval I was seeking owners of 226be/228be speakers-and/or other speakers with beryllium tweeters-who might share any experiences they have had with bi-amping them, and perhaps also doing so using some of the amps in question.