I've had my 250 for almost 5 months now and all was fine. Three days ago it suddenly switched itself off after about 1.5 hours of playing in the morning. It then kept switching itself off after various short intervals. I took it to my Arcam dealer and, of course, he had it playing all day and no problems. Now, I used to have my DV27a on top of the amp so was advised that it was probably heat related and to let it breathe. Now the amp has all the room and air that it could possibly want but it persists in turning itself off after 1.5 hours from cold. Can anyone help?