Y300 call quality

[Guest dus40]

I find that call quality on my y300 is ugly (too many bass). Do you know a way to boost treble in call sound ?

I found this http://androidforums.com/droid-how-tips/18639-read-improve-call-sound-quality.html

 but it doesn't work... I'm on stock 199 repack (sound quality was the same on others roms i have tested)

Thanks