I have had it on playing music from different sources for about 7 hours now and have ensured that it has gone through a few heat cycles. All good. Today I brought out the turntable to test the phono stage and it sounds really good. I am really pleased with how it turned out and it sounds really good. I am not sure I would buy one to restore as it is pretty difficult to work on, but if you can find one in great shape at a good price it is a solid performer. Did a check on the serial number and this one was built in Jan 1977. I love stuff that is built to last.