Pre-amp suggestions for Thiel 2.4/Pass Labs XA30.5

I'm not surprised, but at least you absolutely know for yourself, nothing beats that. If you like Nelson's Class A offerings, but your power requirements and budget only allow for Nelson's Class AB amps, you might want to consider his older Threshold S series amps. They were biased to stay into Class A for the first 20% into their 8 Ohm rating before sliding into Class B, however when they double power down into lower impedance's i.e. 4 Ohms, the biased is halved as well. Still this more Class A bias than the Pass X series, and even with the cost of new caps, re-bias etc., less expensive too. Just a thought.

I have been using a Bel Canto REF1000M with my Thiel CS3.7s and the 2.4SEs before that.

I have heard the Electrocompaniet Nemos and they sound incredible with the Thiels.

I am a bit curious how the Plinius SA-Reference would sound with them. That delivers 100W of Class A into 8 ohms in stereo mode.

What do you folks think about something like a set of Aleph 2s? Quite a bit cheaper than the X250.5, not as much power, but at 200W into 4 ohms, they should be a better mate to the 2.4s than the XA-30.5...

I did mention briefly the possibility of going to something older like the Aleph 0 to the Pass folks and they pretty unequivocally said to do the 250.5... just because the older designs have so much more distortion.

As popular as the Aleph's were/are, they weren't my favorite Pass amps (though I do love the industrial pragmatic look). FWIW, I found them lacking in dynamics. Keep in mind that you wouldn't be getting much more power into 4 Ohms than you currently are with the XA-30.5. Pass is to be commended for suggesting you buy an amp, whether from them or someone else, for your speakers, rather than switching your speakers. That kind of refreshing integrity is priceless. With that said, and within your budget considerations, the Pass X250.5 seems like very sound advice. FWIW, that's what I would have suggested you started with from the beginning. I suspect you'll get a good price for your otherwise very fine XA-30.5 from someone who truly understands the amp, and has the appropriate speakers/room to appreciate it. It might have been a little costly, but I imagine that the journey has become somewhat interesting and educational? At the risk of appearing redundant, don't be afraid to consider an older refurbished Threshold. They don't pop up all that often (people tend to hang on to them), but you might be surprised by the high quality value they offer. You can probably resell it at it's cost to you in short time if you don't care for it, the only penalty being it's admittedly not inexpensive shipping costs.

Owned the Aleph 3, 2, and J - and loved them, but I would describe them as amps that do best with speakers that are tube friendly - highish and smooth impedance - non are real current monsters, which is what I think a speaker like the Thiels or Maggies need.

Just out of curiosity, does anyone know what amplifiers Theil has used at shows the past 5 - 10 years? Likely a good match. I actually heard 3.6s with ARC VT100s a few years back and that sounded pretty darn good, so even a well designed tube amp with enough power should work.