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?

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As an X250.8 owner with a First Sound tube pre amp I find that an hour or so is all that’s needed to achieve 100% optimum playback sound quality.  If the system improves after 6 hours I’m unable to hear a difference. 
I am very surprised that ZOTL 40 is powerful enough to drive Maggies. For Soundlab panel speakers, they recommend >200 W, like Atma-Sphere MA-2.
There seem to be some pretty darn good Class D amps hitting the market. High wpc &  Low cost. Are Sound labs bi-ampable?

Or buy a couple Magtechs from Roger Sanders and solve all
your power needs. 
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.