Ultralinear vs. Triode vs. SET

If your Cronus already provides enough power for you (55 watts?) and you wish to try SET, get Audio Mirror 45 watt SET monoblocks. Nearly the same power as your Cronus, but SET! Glorious amps.

" From both a technical and sonic perspective, what are the differences between a tube amp with switchable ultralinear and triode mode vs. a true SET amplifier?"

A tube amp with a UL/Triode switch will most likely be using a pentode. The switch makes it operate "like" a triode but it is what it is and some may like the sound of a KT88 or EL34 wired that way but it's not a true triode. A true "SET" amp will probably be using a 45,2a3 or 300b tube each having their own flavor/character and power output.

That's kinda general but the best I could do per your question and keep it simple.

I do think anyone who loves music should at least give a listen to a "true" SET mated once in their life. Hopefully it will be mated to a speaker it likes.

Ooops, was rushing at the end of my post. Last paragraph, delete "mated" after SET.

Very simply: a pentode based amplifier will be more versatile with speakers. A SET is very finicky and will like some speakers and music more than others. Despite the poor measured performance of the SET, it somehow manages to sound more realistic and more believable than any other amplifier type ... provided it is matched with the right speakers and the right type of music.

Thanks for all the great replies so far. A couple of additional questions:
1. Would a single ended pentode amp typically have the same sonic benefits as a SET amp?
2. Would a push pull amp with no negative feedback potentially have similar sonics to a SET amp?