just tried this cause in general i've been missing this feature a bit in mplayer (gstreamer just uses more cpu).
in general it seems to work, but somehow it screws up my progress-scale widget and the pos-widget. the overall runtime of a song sometimes gets exceeded by the counter (especially when skipping towards the end of a track to try the gapless feature
also: would i have to create the pipe and the aplay instance everytime i start gmb? (not that this is a problem, i could simply make a script for that.) i don't know much about pipes in linux, do they have to be closed again?