Hi TB, Just got an Ampeg PF-50T. Great amp, love the tone! (Ampeg fanboy) However, after about 15 to 20 minutes of playing, the amp starts to make a sort of rattling sound. I recorded a short clip this weekend: (kids were in the room, that's NOT the sound I'm talking about ) I have tested this multiple times and it's always after a bit of playing that the sound occurs and stays. So I presume whatever is happening is only happening when the tubes are fully warmed up. When I up the gain and volume, the sound gets triggered more easily but it's not necessarily louder. When the amp is not on top of the amp, the sound is less present but not totally gone. So I presume something is vibrating that shouldn't be vibrating. I have used the same cab (Barefaced Gen3 Super Twin) with my V-4B reissue, my PF-800 and Micro VR heads and never heard something like this before. Since it's a new amp, the most sensible thing to do is to just return it. But I'm not keen on the idea that the amp would be sent back an forth... So if there are some things I could check myself, I'd love to know them. Thanks!