Sorry for the late reply guys, I just woke up and I posted the fix midnight right before sleeping.
Honestly I found the fix all by luck/ trial and error. I downloaded all roms for the S3 mini (both stock based and cm based).
Starting with the stock based like (DMOD, enox benz) - all had working a2dp but none of their 4.1.2 BT files worked with cm10.1
Then I went ahead to try all the cm-based roms (even from early on like cm10, cm10 beta, cm10.1 alpha and so onn...)
Only one cm10.1 rom had working a2dp and it was team Maclaw's build from 6/26/13 right before they shifted to their new kernel 3.0.84
So I tried all BT files and finally isolated it to libbt-vendor.so which was compatible with cm10.1- but only based on 3.0.31
Sorry will revise my post right now and will give full credits to Maclaw's team
Try it guys its really working!