Pass Labs x250.8 vs tube amps


I have a beautiful system. Lumin X1 > BAT Rex 2 pre > Pass Labs x250.8> Sound Labs M545 (ESL) in a tiny room (9x 11 ft).  This system has the most glorious SQ: smooth, detailed and powerful , along with great bass. I would say this sound equals or betters any ultra high end system. HOWEVER, I have a problem. My system takes 6 hours of music playing to sound this good. I had X250.5 and I had the same issue. Leaving it on idle overnight doesn’t solve the problem. It is 15 W class A, so it generates quite a bit of heat, and yet I have to still play music. Because my room is small, I don’t crank up too much- maybe this is the problem, but the temperature doesn’t complete stabilize for 5-6 hours. The top reaches 107 deg in 2 hours, but the front plate doesn’t reach 107 until the 6 th hr when it starts to sound glorious. I have never had a tube amp and I am wondering if I can reach that thermal equilibrium and the glorious SQ faster with a tube amp? I worried about the heat generation with a tube amp in this small room, but X250.8 generates 450 W just idling. This is no worse than tube amps like Audio Research 150 Se, which I demo’d and was impressed by. BTW, I need power in the amp because of the esl speakers.
What do you all think?

128x128chungjh
Sound labs are not bi ampable. Anyone have experience with high end D class amp?I know they are generally poo pooed, but who knows-may be there has been sufficient progress recently. 
My Viva "Solistino" is an 18W class A integrated  amp. I usually  turn it on for 10-15 minutes for warm up, it does sound a little better after 30 mins. And the IA runs very hot.....can't imagine a system that takes 5-6 hours to warm up.
@chungjh
Sound labs are not bi ampable. Anyone have experience with high end D class amp?I know they are generally poo pooed, but who knows-may be there has been sufficient progress recently.

Class D you say?  How about Tube + Class D monos 600w @8ohms.  Effective to drive your Sound Labs, with ease. Quick warmup, and ready for listening. https://www.psaudio.com/stellar-m1200-mono-amplifier/
PS audio Mono 1200s.  Ultra-linear, high-current, ICE Edge Class D technology for the output stage; and a discrete, Class-A vacuum tube for the all-important input stage. 
I think @ebm is right.
I use a X350.8 and I believe your X250.8 is warmer sounding. I don't think it will ever be the same as a tube power amp.
I like a warm and full midrange and don't think any solid state power amp will ever give me that close enough to say a Conrad Johnson. If my speakers didn't need the high current and I could live with the heat and cost of retubing, I would have gone for a Conrad Johnson.