I have owned a 27 and 27.5 and they never ran hot as you are describing. Did your repair shop check the caps, resistors, etc? Have you used Google to research this issue? Personally I wouldn't use this shop any longer because they haven't found the issue plus I would be reluctant any way to take the amp back as they want you to trade up. To me thats a flag especially trading for a Bryston 4B. Not that it is a bad amp but the 23.5 IMO is quite a bit superior sonically.
Mark Levinson 23.5
I was at my local dealer yesterday because I am considering purchasing some cables down the line. He gave me 2 brand new sets to audition and told me since they are brand new they would sound best after the burn in of about 30 hours or so. I plugged them in to my Mark Levinson 23,5 and its been on playing all day (about 10 hours) at a normal to lower volume. My thought is, I'll just keep the system on and audition the sound periodically in between. I don't know if I've ever had my amp on this long. It seems to be getting very hot. Everything sounds absolutely fine. Does anyone know if these amps normally run hot after extended hours of play. It's not even being driven hard. I'm concerned because I just got the amp out of the shop last week after being in there 4 weeks the first time and then 9 weeks the second time. When I received it back the first time, I received it back with a noise issue. Nothing has changed impedance wise. Any thoughts out there?