I have an old Audio Electronic Supply AE-3 that has developed this issue that I am pretty sure did not exist before. Without an audio signal and regardless of volume position there is this static "putt putt" noise that occurs every 2-3 minutes and always in pairs only. It is not the tubes or the environment because it occured in my previous home as well regardless of tubes used. I never hear anything strange during music playback but as soon as music stops, there it is. The .22uf coupling caps and the output caps were replaced a year ago. Sounds glorious with the Audiocap Theta and Claritycap ESA combo.
Looking for ideas on what to check next. Thank you!