Hmm, this made me look deeper into it again, and I found some clues which I never had before:
I have the habit to run apps which access sound device under aoss wrapper to prevent them from being blocked by another app accessing sound device.
Running under aoss wrapper:
32228 31277 tc       R     3928  0.7   0 29.2 mpg123 /mnt/sda1/sound/rumble.mp3 
32191 20893 tc       S    21644  4.1   0  7.5 mplayer /mnt/sda1/sound/rumble.mp3Running each one exclusively without aoss wrapper indeed there seems to be no significant difference:
 2207 31277 tc       R     2400  0.4   0  5.2 mpg123 /mnt/sda1/sda3/sound/rumble.mp3 
 2310 20893 tc       S    20404  3.9   0  4.9 mplayer /mnt/sda1/sda3/sound/rumble.mp3The plot thickens when running mpg123 with "-o alsa":
 2542 31277 tc       R     3856  0.7   0 13.7 mpg123 -o alsa /mnt/sda1/sda3/sound/rumble.mp3using much more cpu than without "-o alsa", but much less than under aoss wrapper.
When running mpg123 with "-o oss" then it stays in same range as without any parameter:
 4563 31277 tc       R     2400  0.4   0  5.2 mpg123 -o oss /mnt/sda1/sda3/sound/rumble.mp3I am a bit puzzled now, does that mean that without parameter mpg123 would use alsa module oss emulation and use much less cpu than with native alsa?? 
