here is the trick: this player with 8-pins chip is palying raw WAV by using PWM. Attiny85 has 2-channel high speed PWM, so it is very sutable for this, as it does not need output low band filter after high speed PWM.
Thats very nice! I thought about that in my post
Well, does the ATtiny85 emulate some filesystem for the SD card or
just read the data blocks from it ?