Which high power SET

I hate to pop your bubble but OTOH, I will probably save you a lot of heartache too so:

The Harbeth is a revealing speaker but not particularly efficient. Its efficiency (and efficiency matters more to tube amps than sensitivity FWIW) is low- only about 85 db. For those that think it is higher keep in mind that Harbeth rates in sensitivity and the impedance of the speaker is 6 ohms. When you do the math 85 db is about right.

You will find that you are better off with a push pull amp that can make some power. There are several reasons for this, not the least of which is that the more powerful the SET is, also the less bandwidth it has. In this case any 20-30 watt amp is going to fall on its face right away.

To take advantage of an SET's characteristics (low distortion at lower power levels) you really do need some efficiency, at least 10 db higher than what you have for the amps mentioned. The only caveat here is if you plan to listen in a small room and in the near-field. Otherwise, seek a 100-200-watt amplifier for the average American listening room.

Edoit,
Atmasphere makes a good point and his reasoning is sound. However if there's any chance you can hear one of those premium SET amplifiers with the speaker, please do so. From personal experience I can say that expectations aren't always reality. Those are "very good" SETs on your wish list. Depending on your taste, music genre,room size and listening volume they could be just what you want.Compare them to a higher powered(pentode tubed) push pull amp and decide. You may be pleasantly surprised by what you hear.DHT tubes are capable of producing beautiful natural sound.
Good Luck,
Charles,

I'm using a push pull 30W and it's more than enough for my listening tastes. Hence the thought of SET for more refinement. To rephrase my question, which of the 3 on the list would be the best match for shindo masseto pre amp?

I doubt that there are many here, or for that matter anywhere, who have heard your particular combination of gear with the three candidate amps. I have only heard the WAVAC and the system sounded quite good so it is a possible choice.

I own a low-powered SET amp (parallel 2a3) as well as a pushpull triode amp (45 tube) and a pushpull pentode amp (349 tube). All of these amps sound different and quite good. I don't think one should be completely committed to one particular approach as being inherently better than another. At this time, the pushpull pentode amp is in my system because it delivers the most realistic sounding midrange and punchier bass (though not as nuanced bass as the parallel 2a3). In other words, if you are looking for something better than your 30 watt pushpull amp, candidates for "better" may be another pushpull amp from a different designer or one using a different tube or design implementation. I would personally be wide open to trying different options and I would insist on hearing these options in my particular system.

I have heard 211 and 845 SET amps in various systems and they can be very good sounding. But, at least when run in extremely efficient systems, these amps don't deliver quite the same sound as a 45 or 2a3 SET (the amps I generally prefer). I suspect that every choice has certain tradeoffs and one must listen and decide which tradeoffs to make.

I think that where some power is really required, but not extremely high power, OTL amps should be in consideration. These amps are amazing when it comes to perking up the sound--they are fast, dynamic and have oodles of "presence" without being overly harsh and unpleasant. Some may not exactly fit into the category of being "refined" sounding, but, you may change your priorities once you hear them. Like any kind of topology, diffent implementations are voiced differently so you would have to hear the different choices. I happen to like some lower-powered SET amps because they can deliver a lot of the same kind of lively sound of OTLs (taking into account there MUCH lower output), but one really must have ultra efficient speakers.

Larryi,
Many good points you've made as usual. I agree that no single amplifier or particular topology is perfect, they all will require some degree of compromise. The key to ultimate success and long term happiness is knowing what type of sound/presentation you truly want. I stuck with the SETs since this is what Edoit expressed interest in. I believe that he's headed in a very good direction with his list of candidates.

Edoit you say that you current 30 watt amplifier is enough power and pleases you, that's important information to know. Based on that I'd strongly urge you to listen to the 845 SETs you're curious about. Given your comments it suggests that high quality 30 watts is satisfactory with your speakers. Quality will often win out over quantity with the appropriate speaker match. As Larry said an OTL is a viable option (they all sound different depending on the brand).Personally high quality SET amplifiers are the closest I've heard to mimicking the live venue experience. That's why I'm very supportive of your pursuit of them. Naturally YMMV.
Best regards,
Charles,