40+ watts SET, cost is not a problem

If you are really insisting on SET, and want the best of that sound, to me it is low-powered SET, and anything close to 40 wpc is out of the question.  I have only heard a few 833 and 1610 and other high-powered SETs, and never in a system I am familiar with, and I did not think the sound was special.  If the speaker is not well suited to SET use, why would you want to either shoehorn in a less than ideal amp, or take the opposite approach--shoehorn in an inappropriate speaker into a SET-based system.

The best sort of higher-powered SET amps I heard were Audio Note Gaku-On monobloc amps (parallel 211 SET) that sounded great with a wide range of speakers, including somewhat difficult speakers like Harbeth 40.3s.  But, those amps cost as much as a house.

I personally don't subscribe to the notion that SET amps deliver the very best sound if one can live within their restricted power output.  I do like the sound of some of them (I own an Audio Note Kageki parallel 2a3 SET amp), but it is not even my favorite among my own amps; that honor goes to a 349 pentode amp.  The best ever amps I've heard were a custom built OTL amp and the very ancient Western Electric 59A amp (252 pentode amp).

There is a Golden Tube Audio SE40 amp available now on eBay for $1000. It uses three 6L6GC beam tetrodes in parallel per channel It is single-ended, no phase splitter. I own one. Tube replacement is far less costly than 300B's, 211's, 845's ... You might want to check it out.

@larryi ,

You mentioned:

“The best sort of higher-powered SET amps I heard were Audio Note Gaku-On monobloc amps (parallel 211 SET) that sounded great with a wide range of speakers, including somewhat difficult speakers like Harbeth 40.3s.  But, those amps cost as much as a house.”

Would the Audio Note Jinro 211 Set amp maybe be a possibility also , for less money?

@larryi when you refer to gaku-on, are you suggesting Kondo or AN UK?

Secondly, which other tube amp (non-SET) would you suggest with at least 80-100 watts which have top tier sound?

I have heard the Jinro in several systems, including one with AN-E speakers where I am familiar with its sound.  The Jinro is a good sounding amp, but, it seems just a bit too laid back and not as exciting and vivid as I like.  

For a non-SET amp with 100 watt or so power, I am a big fan of the Synthesis Audio A100 amp (KT 66 tube).  This is a punchy, lively, and warm sounding integrated amp that also has a built in DAC that is pretty decent.  That it is a screaming bargain makes it hard for some people to consider it in a very high end system.  Perhaps one of the Synthesis separates, then, for those who want to spend more than the price for the A100.  

The Gaku-On that I am familiar with is an older Audio Note (uk) amp.  It is a quite versatile amp that sounded good with any speaker I heard it paired.  I have not heard much Kondo gear.  The one extensive experience I had was when I auditioned a pair of Stax 007 Omega2 headphones.  I bought the headphones based on the audition, but, when I told the dealer I was not getting as good sound from the phones as I heard in his audition, he replied: "of course not, you heard them through a Kondo M-10 and you don't own anything like that."