What would you say is the better sounding SET amp?

Friend

The nod goes to the 45 as the best of the tubes you listed. My experiences are:

45=Very honest and sweet with the entire frequency spectrum.

VT52=No experience with this tube.

2A3=Great detail over the entire frequency spectrum -but too thin in the lower octaves.

300B=Exaggerates the presentation.

845=Very nice and honest presentation. Almost as sweet as the 45.

EL34=Very sweet and romantic performer, but simply cannot do what triodes do for the presentation.

6550=Sounds like a great stereo - not a real presentation.

KT88=Better than the 6550, but still not a real presentation.

My fav, is the WE300B, with Wavelength Cardinal X1, the bass, midbass is all there, the Mid range is holographic, and the treble, airy, without being rolled off. JMHO.

I love my Korneff especially with the addition of the Mullard ECC32=CV181 input drivers.. This combo is really nice. Although.. my overhauled and hotroded GTA Mono's using KR300BXLS Tubes is just as good and then some. The Korneff 45 is incredibly detailed and intimate. The GTA's sound equally delicate, but they have slightly lower floor noise with unbelievable power reserves. eg trumpet blat - which seems to come from now where, and just about pins you to the back wall. Large orchestal passages are explosive and stagering HUGE. The Korneff dosn't have that kind of explosive power. I am using Khorns -biamped.. They can be a bit forward.. so The Korneff is a bit well - a bit softer, easier to listen to .. I enjoy both amps immensely. The Korneff 45 is my daily choice. For real authority I connect the GTA's. But hold on for a ride.

Different horses for different courses. Aside from the difference in power output, the tubes do differ in ways that make one or the other more ideal in a particular application. I generally find the 45 tube to have an ideal tonal balance and beautiful sound, without the 300B tendency to be overly lush and wooly sounding. The 2a3 is much leaner than the 45, but it sounds very fast and detailed and has a beautifully extended and airy top end.

In my system, both 45s and 2a3s work well. I am currently running 2a3s in parallel single-end configuration, but I also have a pushpull 45 amp that sounds nice.

I am very very happy with my 45 SET.
You need very efficient speakers with it.