forbiddenhex has written an article detailing how to turn a TP-LINK TL-MR3020 into an Audio player:
This time i flush the TL-MR3020 with Openwrt. After couple of usb packages and audio packages i just plug in the USB sound card (which was given by whoknowz – to the router.
When the USB sound card is detected from the linux, you can check by command dmesg. Then install the madplay or any player you prefer.
I installed madplay because it play audio streams and play local files.
For test i played the audio stream from atoll radio and it works great. Just ssh the router and pass this command wget -o – http://radioatoll.serverroom.us:7088/ | madplay –