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?

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.
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.
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.
BTW, I need power in the amp because of the esl speakers.What do you all think?

To: @chungjh
I don't typically recommend dealers, in your situation it could be worthwhile to correspond.  A local home audio dealer (Deetes) here in northern California USA has been in business since 1967, offers SoundLab speakers, sold Pass, more AudioNote and QuickSilver today.  Primarily traditional TUBE amp systems only - that's his real passion, and specific electrostatic speakers.  He's actually been selling SoundLab speakers as long as anyone around the world.  I've known him for 42 years, seen and heard a lot of gear there new, used, trade-ins. A real treat to hear Soundlab there.  Its a special place, last of its kind. 

The first time I saw and heard my own mono block tube amplifiers they were playing with massive SoundLab speakers there. Deetes is a big fan of your SL 545s too.  Email and by appointment only.  In business 53+ years.  

Deetes Sound Room
Deetes Andersen
Former related thread four years back, some good replies by Agon’ers, @atmasphere

Thread: "Why Warm Amps Sound Better".