2. amps-preamps
  3. 161353-98013

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
mammothguy54's avatar
mammothguy54
949 posts
 
I own a BAT VK-33SE preamp and VK-255SE power amp.  My speakers are 88 Db efficiency.  The amp drives them effortlessly, with plenty of safe headroom, and I find it to sound it's best after about 30 to 45 minutes.  It gets quite warm by 30 minutes, maybe you could say hot, but never a room heater.  BAT products work very well with one another.  They are designed and engineered to do so.  The VK-255SE amp is one of the most "tube-like" sounding solid state amps available.  Since you have a BAT Rex-2 preamp it would be a very good decision to match it with a BAT power amp.  That's one suggestion.  Another suggestion is to get a BAT tube amp.  The Rex-2 power amp (as well as the Rex-2 preamp) have both been recently replaced with the next-generation Rex-3 products.  Thus, the Rex-2 power amp can likely be had at a nice discount.  You may wish to contact Upscale Audio about that.  They have a Rex-2 power amp set up as a demo unit.  It is only switched on when a demonstration is requested.  I visit the store fairly often and can tell you that amp is in absolute perfect condition.  Upscale Audio is a wonderful retailer to do business with.  I am confident they would work a nice price for you on that unit.  Anyway, I thought you may want to take into consideration pairing your preamp with the engineered mate of power amp and also provide you with a very good path for such opportunity.
Best of luck to you. 
gkr7007's avatar
gkr7007
153 posts
 
Chungjh
I have an LTA reference 40 amp paired with a Don Sachs preamp.  I used to drive a pair of very difficult Maggie 3.7i's with this setup and had no problems.  That amp is a giant killer if there ever was one.  Just stunning.  Keep in mind it's not necessarily watts you are looking for but current.  And those el34 tubes give you plenty.  I would try one as you get a 14 day no questions asked return policy.  You may be greatly surprised.
markmendenhall
224 posts
 
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. 
chungjh's avatar
chungjh OP
265 posts
 
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.
chorus
976 posts
 
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. 
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