After a lot of research about that KitKat 4.4.2 bug i found the cause of the problem. The audio glitching bug is because of hotplugging of the cpu cores. A common bug, as someone told at Xperia Z forum section. To fix this, disable mp decision through Trickster MOD (Search for it at Play Store). This should fix it. But this also means your cpu no longer shuts off cores when not needed. But it shouldn't affect your battery usage much... At Trickster MOD the Mp Decision is located at "Specific" tab. You ONLY need root to make it work!!! Tested by me!
You can re-enable MusicFX and Sound Enhancement without problem now
P.S. If you restart your tablet you have to disable Mp Decision again cause it will return to the default value.