Popping sound on SACDs from Ayre

I have the same player with the “mp” upgrade and have never experienced this issue. I have had a few small issues and found Ayre to be very supportive and responsive to render a solution. I would contact them as this may be a minor fix and they can direct you to the solution without sending it in.
But my first thought is that the software that analyzes the format at the beginning of the disc and each track is struggling in identification. One thought as you don’t mention, is watch the display when you hit play and see if the SACD indicator flickers or even toggles to CD then SACD. It would probably be a very quick indication if there at all.

I have that player too and I experience a small single pop when first playing an SACD. As far as I can tell, it's normal. I think it's because the player is switching in the SACD decoder.