i text matin's patch on my w610 cid 52 db2020.it don't work...
the sound quality is very low and decrease the volume about 100%
the handsfree port didn't work and the music still on back speaker.
at least fo db2020 that i have tried the acoustic files should be with .zapf extension and not .apf

now i replace it with my last one.
you can find some accoustic driver for db2020 in
SE-NSE Forums -> Download Manager -> Acoustic (.zapf)
i try the (PERFECT-MIX-ACOUSTIC) the back speaker work a bit better but the handsfree work much louder.