I Use Lakka… Lakka is very good on my RPI3 and works better as RetroPI. And ya How i Can add ah “Mp3 Player” on the XMB? Mp3 Songs can play mit FFmpeg. This worked but search ah player as by Playstation3.
And my Archievments not Syncronize with my Retroacount. I am Logged in the Account (via Config) an this not work.
Sorry for my bad Englisch I come from Germany und have Problems with Englisch ^^