Interesting to see comments on 845 v. KT88/90. They really are two very different experiences, though each can be used in circuits designed around them to deliver good results to the same sonic objective. In both cases, of course, amp-to-amp variance in sound is huge. But as a long-time user of a series of KT88 amplifiers, and current owner of KT88, 845 and 300B PSE monoblocks, I can say there's no general answer to Bartok's question of whether 845 amps are sonically "warm."
The only answer is, "sometimes," or "it depends."
In my experience, KT88/90 amps, whether PP or SE, are quite tunable via tube selection. In my Audiopax 88s, Russian KT88s are dry and relatively lifeless. Chinese KT88/KT100 are fast, wideband and cool. Current Russian KT90s have no advantage. Yugo KT90 Type II and Type III are robust, sparkly, open, fast, with tight defined bass. KR/Tesla Vrosovic KT88s are expressive, revealing of finely-etched details, well-balanced. But NOS British Gold Lion KT88s trump everything with creamy power, excellent bandwidth, low noise, big-T TONE. And then there's the Timbre-Lock adjustment to tweak. I had pretty much the same experience with these tubes in Acoustic Masterpiece and Audion single-ended amps, and in various PP, though in PP the differences were much smaller.
The Audion Black Shadow monoblocks, on the other hand, are profoundly affected by tube choice. The common-as-dirt Chinese 845"A" is unspectacular, dry and soft. The Chinese 845B sounds substantially more robust, nuanced and extended on both ends. Bottom leans to the soft side with some euphonic bloat, but not tubby to the point of distraction on Zu Definitions (lower limit below 20Hz). The later Chinese metal plate 845C, a little light in dissipation, is more like the KT88 -- brilliant and sparkly, with tighter bass than the other 845 variants, but also less drive and Tone. The KR845 is very objective sounding for a big triode tube amp, but sometimes is unreliable. Transients are fast and bold. The new Shuguang 845C, with a full 845 dissipation rating, is rumoured to be excellent when it works, but I haven't had a pair in my system yet. Then there are the vintage NOS RCA and United 845s that cost more than some new 845 amps. Undeniably excellent, in a good circuit they deliver a highly objective sound and softness or bloat can't be blamed on them.
As always, transformers are critical. Given the right tube, I can put a KT88/90 amp in a system and give it triode warmth, and can just as well build an 845 system to have a measure of pentode/tetrode ice.
I've heard the Consonance 845 amps. They are good value for their price.
Phil