experience with Threshold SA/2e or S/500 amps?

Any of thr older Thresholds ( specially the S series ) are great and powerful amps. The S A series being the cream of the crop..Compared to today they are still considered very good,but today for some reason the amps are Voiced a little different in my opinon.The Tube amps are Voiced to sound less warm with a more neutral/analitcal sound and Solid State amps have more musicality with more warmth and both s/s and tubes are very close in sound.That being said its very hard to compare.. If you can find a nice SA 1 or 2 Threshold,jump on it before someone else does...

I own a Threshold S/300 amp which I prefer over many more modern poweramps. The sound (to my ears that is) is a bit on the warm side, but not at the expense of detail. It is dynamic, powerfull, has a very nice stereo image and suits my taste to a tee. Also it has plenty of power, which is a good thing considering the (in) sensitivity of my loudspeakers. I recently had it revised and, apart from some small capacitors, it was in perfect shape. The only thing I really don't like are the small speaker terminals at the back, but that's about the only weakness I can think of.
I imagine the S/500 will sound about the same, but with more power. And don't let the words 'Class A' fool you: it is not the only way to audio nirvana. There's nothing wrong with a good designed and built Class B amp.... Like the Thresholds!

Don't get too worried about the S 500, look for the S500II Stasis version. It's Class A to about 50 watts and then turns to Class A/B.

Nice amp, accurate, what you put in is what you put out.
I sent my Muse 160 II amp that had been doing sub duty for me for some time back to Muse. In it's place I had S300 II stasis, and put it in, not as big a difference as going from a B&K 442 to the Muse, but it was there, my subs integrate a bit better with the maggies which is no small chore.

Some people will laugh but, a sub amp makes as much difference as a driver change. Even a non audiophool buddy heard it one night.

He's an old friend and spending the night with his wife, so us phool were up late consuming adult beverages and as
we were feeling no pain, and I being in an X-perimental mood, swapped out the B&K for the Muse between sides of MSFL I-Robot, wholly smoke, he asked what happened. The B&K ain't no slouch or lacking for current drive, but it sure made a HUGE DIFFERENCE. The T-hold was even better.

loon

I use a slightly modified S/500 Series II. I would describe it as very dynamic, open and neutral, but, not necssarily warm. The S/series are class A/AB, the first 20% of their power running in class A into an 8 Ohm rating. The pure class A SA Thresholds are reputed to be warmer and more recesssed. I'm confident that any of the Threshold's with enough power for your room and listening levels can "control" your speakers. The SA and Series II amps are reputed to be more stable than the ealier versions. The factory e series provides for true balanced (upgraded versions have XLR in-puts, but aren't truly balanced) twin trannies, and are DC coupled. The e series are said to have tighter bass, but, the earlier single ended amps are said to have a sweeter top end.
I'm not familiar with your speakers, other than they are not particularly easy to drive with their 4 Ohm, 85dB rating. The S series will double down, but as they do so you may expect their level of class A opeation to halve. If you prioritise warmth; go with the class A SA/ amps. If you prioritise power; go with the higher powered class A/AB S/ series. The higher the power of the S/ series the more base class A you'll get. Perhaps the S/450e might be worth consideration. The older the amps, the more likely they may be need of a tune up with perhaps some new caps. Jon Soderberg of Vintage Amp Repair can be relied on to do this correctly.