Can't get 5.1 from aac format in mpc-hc only stereo

Here VLC covers on top apps in fullscreen just like MPC-HC.

Only way to get this changed is to program a 'fix' yourself and submit it as a patch for MPC. I still don't consider it a bug or something I am interested in working on.

There is however a workaround that you could use. Maximize the window and then press 1 to hide all controls and borders. It will then look similar to fullscreen. Press 3 to reset view.

Wait, are you the coder of MPC? And me submit a patch? I thought it was a dead project?
Alas, I'm no coder, and like I told you from the very beginning it's not that big of a deal.

That's a pretty interesting workaround though. I might actually use that method when I specifically need the gadgets visible. Thanks!