Ultralinear vs. Triode vs. SET


I currently have a Rogue Cronus that I have been quite satisfied with, but I am intrigued with the possibility of a SET amplifier. 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?
droz
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?
HI All,
For me, the prime drawbacks of SET amp is their low power and restricted frequency response/dynamics. I won't argue against their mid range. It's great.

My problem is I have never heard a high efficiency speaker that I would die for. Yet, these are the only speaker types that a set amp can drive. This plus they basically sound like active tone controls.

No thank you.

Sparky
Maybe take a listen to a tube amp where the tubes are direct heated. I think Coincident makes one like this. More of a SET sound with frequency extension.

Happy Listening.
Hi Droz,
I was in your shoes about 14 months ago. I prefer tubes over SS amps and had been using push-pull(PP)amps with mcuh satisfaction. These amps were pentode/triode switchable and were El34 or KT88/6550 based. Well after reading reviews and articles concerning SET amps my curiosity got the best of me and I purchased the CoincidentMK2 300b monoblocks.I`m absolutely hooked on these amps they`re just fantastic. As other posters have said above a good quaility-well designed SET amplifier just sounds so naturally real and live. The tactile and palpable presence is the best I`ve heard compared to SS amps and even very fine sounding PP amps. The sound is very organic, fast and dynamic, yet it retains such a relaxed musical flow.
I disagree with those who say you give up upper and lower extension for sake of a great midrange NO YOU DON`T! This is a misinformed stereotype Droz. The key to sucess is matching to a appropriate speaker(high effiency and favorable load-ohms). You do not have to settle for rolled off highs or soft/flabby bass. You will have many choices in different DHT tube types and also various speakers. Just be patience in your search and read many reviews of SET amps to increase your knowledge base. The world of SET can be wonderful with the proper approach. I hear nuance harmonic overtones and micro detail that were hidden with my PP amps.
All great information, but not all of it true for all SETs. I love my speakers (87dB) and did not wish to give them up, but did wish to try a true SET. Thankfully, Audio Mirror 45 Watt SET amps are true SETs, yet very powerful, and not lacking frequency extension in any way. If you love your speakers and wish not to change them, you owe it to yourself to try a true, powerful SET. I believe there are a few other manufacturers available with true powerful SETs as well. Swapping the stock driver and input tubes with NOS took my system to a whole new level.