Many people have complained that with certain drivers KDE doesn't work correctly.
Here's the general settings you can use for KDE (applicable for all OSS device drivers)
1) Select KDE Start -> "Settings" -> "Sound & Multimedia" -> Sound System
2) Under the General tab disable "Run with highest possible priority" - this is not needed
3) Under the Hardware tab select Audio device as : Threaded Open Sound System
then set the Use Custom sampling rate and set it to 48000 Hz
then set the Quality as 16bit.
Save and exit and restart KDE.
