Mixmonitor quality

Hi All!

I am trying to get better queue-recordings files.
Tried to change the format, but I didnt feel better quality.

The A-sounds (local) is fine, but B-sounds choppys/noise a little.
This occurs only in the recordings! During the call conversations, the sounds is good! No choppy/noise.

Is a MixMonitor problem? How can I improove its quality?

My Asterisk is
IBM X3200 Xeon@2.4Ghz, 4Gb Ram, SataII 7200rpm, Centos 5.5