I have had all kinds of SET: pure SET, SET hybrid, PSET, SEP and SE(Transistor) hybrid.
Currently at home I have the following:
JJ-322: 20 watts 300B PSET and this amp with the right speaker (read > 93db) it sounds very punchy and transparent with good deep bass. It has very nice and large double C core output transformers that assist in the clarity IMO. Sounds very good on both my Odeon horns.
MasterSound Dueundici: Little firecracker of an amp that drives my 96db Decware HDTs. Good bass and transparency but not the last word in soundstage depth or 3d imaging, which I think may have to do a bit with the pentode operation and/or the bit of negative feedback that it runs. Still, good clarity and fine for the late night listening duties. The larger DueVenti can also be run in triode and I think without feedback that should improve the sound over the Dueundici
Aries Cerat Genus: Our newest "baby" this SET has power out the wazoo and transparency that rivals the very best. Dynamics are also near state of the art. That said, the Diana Forte we have in our demo system is a PSET that is just as transparent and probably more dynamic. The Diana Integrated is a SET (same output power as Genus) and is just as good as the others. So, SET or PSET here there is no penalty either way. A customers PSET Conceros takes it a notch higher all-around though.
So SETs I have had in the past:
Cary CAD-572SE: Great sounding little SETs with a unique "big bottle" output tube. Smooth and liquid but not the last word in any parameter.
KR Audio VA350i: Had three of these in the past and these unique "reverse" hybrid SETs were dynamic beasts that drove most speakers well that we tried them on...worked great on my Acoustats and STAX electrostatic speakers... A really great amp.
NAT Symbiosis SE: Hybrid SET with one large MOSFET per channel for the output and another one for regulation of the output, which resulted in 4 huge heat sink towers (looked like the Battersea power station!). Never had quite the transparency of a top SET nor did it have a really open and sparkly top end but once it fully warmed up (the transistion from ok to WOW was very dramatic with this amp) it was almost psychadelic in its tone and 3d imaging and soundstaging. Bass was also better than most SETs...a truly interesting amp that I might have kept if it didn't take so darn long to warm up properly...and the power consumption was enormous!
Wall Audio M50 monos: PSET with 2 x 6C33C tubes per mono. This was the first PSET I had with this output tube and I can see why people like the sound of this tube. These were perhaps a bit lower in clarity than my other SETs but had a big bold sound that rocked on my big Odeon horns. Kind of regret selling them... but I needed more transparency ultimately.
Ayon Crossfire III: At first, I found this the most analytical of all the SETs I had before. It was leanish through the mids but did have a rather powerful bass and big output trannies. After tube rolling (replacing russian input tubes for NOS GE and the 6N30 driver for 6N6 and the stock rectifier with an Ayon 5U4G) the result was retaining that superb transparency, imaging and soundstage while getting the tone that one expects from a proper SET. The big 62B output tubes could deliver that big bottle umph with more delicacy and inner resolution of a 300B. Perhaps it was not quite as good as a 211 or 845 for grunt and perhaps not quite as good as a 300B or 2A3 for inner resolution and lit up quality but it was a good balance with plenty of both. All-around, this SET is probably the best I have had until going Aries Cerat. Stock not but with the tube rolling it got there. The KR VA350i is right up there as well. Both are lower in coloration than some of the others I have had or heard and that might make them less SET to the the Viva, Cary, Kondo crowd.
Other SETs I have significant expeirence with:
KR Audio Kronzlla SX and DM monos: Beasts and very good sounding...these are actually PSET "reverse" hybrids, whereas the VA350 is just SET hybrid. The DM monos I had for review in 2005 drove my Acoustats better than anything else I ever heard with them.
NAT SE1, SE2SE, SE3: Heard all possible variants of NAT's 211 based amps. On sensitive speakers the oldest SE1 version was the best sounding (it was also huge and had tube rectifier for the input/driver). For Apogees the oldest SE2SE version sounded the best to me (and was a powerful beast that bested CAT JL2 signature as well). The SE3 was also very good sounding and had power to burn. Both SE2SE and SE3 are PSET and didn't give up much on the SE1 if anything on ohter than really sensitive speakers.
NAT Transmitter: Powerful but not as pure sounding...possibly due to the output tube choice which is actually a tetrode I believe.
Cayin 845 monoblocks: These had a more stereotypical warm and full sound. Not overly transparent or energetic but gave a nice pleasing but somewhat colored sound.
New Audio Frontiers 845 integrated (SET) and monos (PSET): Heard numerous times at dealer on various speakers. Both have rich warm sound but very good holographic imaging and soundstage with superb transparency...just a bit of "golden" hue to the overall tone colors but something I think most could easily live with.
I am not convinced from experience so far that PSET is inherently inferior and there are some design advantages with regard to output transformers by going parallel that might more than offset the apparent theoretical advantage of a single tube vs. multiple tubes.
Two of the best SETs I have heard, Concero 65s (Diana Forte) and KR Audio Kronzilla DM monos were both PSET. The KR in fact is 4 triodes per mono because each T1610 tube is in fact a double triode to begin with and there are two tubes per monoblock.