Pass Labs x250.8 vs tube amps

open a window...use a fan.....    You seem to like your sound: don't mess with it.

I think he’s also referring to how much time it takes to warm up the Pass amp before he’s ready to enjoy it. It’s a regular topic. Not unique to Pass amps. My former dual mono class A/AB SS amp was the same way at 6-8 hours, it transformed into a gem once the transformers were good and saturated with heat at 6-8hrs. Parasound has made some progress with 1w standby pre-warming, and even then I demo’d one and still had to run it for a while before it sounded right to me. My mono tube amps I run now take a lot less time to be ready for listening.

@chungjh,
My local dealer sells Sound Lab and tube amps only. I’ve heard various SL model speakers there over the past 20+ years. In every case they were running two mono tube amps with the SL speakers. At 86db and 8ohms for your 545s, you’d likely need a (pair) of tube amps if you do decide to go to tube. More output tubes = more heat there too. Last time I was there, he was running a set like the larger 845s (huge) powered by two Quicksilver Mono 120 tube amps with dual KT150s in each, only 100wpc. One mono amp per speaker. While it sounded very nice, seems like many with your speakers run above 250wpc solid state amps regularly. If I had 545s and could not keep the 250.8, tube amps would be my choice. They do sound quite amazing with good tube amps. Maybe not as dynamic as your 250.8 Pass amp, unless you bought some with lots of tubes and back to heat again, IMO.

Pros/Cons:
While you only need one amp now to power your 545s with the Pass 250.8, you’d likely want/need a very large stereo tube amps or monos, and either case, still generating some heat but maybe less time for warmup.

Warmup:
The advantage I’ve found with my QS Mono 120s with two KT150 output tubes per amp, they have fewer tubes, don’t run hot, and never take more than 1hr to fully heat up, even at 45 min they start to sound pretty good.

Having heard a few different tube amps with your speakers, you’d need to choose wisely with tubes before you could effectively displace a Pass 250.8 amp I’d bet. Would mono tube amps be enough power and dynamics for you without buying some heat-monster tube amps, hard to say. Your speakers call for 50-600w. It really also depends on your room. At lower listening levels, sure might get away with 100w tube amps. Or, fans for the 250.8 and call it a day. Good luck.

Roger West, the owner of Sound Labs, thought Atmosphere MA1 (140W) was powerful enough for room 9x11. Because of lack of space, I was thinking about AudioResearch 150SE stereo. I think heat generation will be similar to X250.8 but will it reach thermoequilibrium by 1-2 hr?

Take a look at the Linear Tube Audio OTL designs.  BTW, all their amps can be bridged if you need/want to.

The dynamism of X250.8 is unparalleled. With drums in Angela Brown's band, the SMACK is incredible. As I get older, I feel like I wouldn't mind with a bit less SMACK.