"unsupported sound format: 33" - This happens on cards that don't support playback of 16bit, stereo, 44.1kHz sound. Try running in 8 bit mode (esd -b), or at a lower playback rate (esd -r 22050), or both (esd -b -r 22050)
"unable to connect to server at port 35091" - This means the client cannot contact the server. Make sure you have SysV IPC enabled in your kernel
Documentation of the API is in sad shape, but for now it's still in development (i.e. subject to change). See the source of the sample command line driver utilities (esd?*) for usage.
Any other pressing issues, problems, or patches may be directed to ericmit@ix.netcom.com. Please mention EsounD and the version number (date for cvs checkouts) in the subject line.