for me, i had to dawn khz to 11 to got clear sound (48 sounds really ugly), but it still be low (volume), but a correct level if my speakers are at max and max in the options... and i did anything else : i have edited the config.cfg file, the entrys "set snd...", especially the one which read sound like 8 bits.
Please forgive my bad English, i'm just french. I just hope you understood ;p