Hello there.

It sounds to me as if something in your chain (most likely the PC itself, or perhaps the sound card) is putting out some nasty RF noise during MIDI data transfers which is being picked up somewhere in your audio - your job is to isolate the piece of equipment that is picking up the noise (by process of elimination).

It's already been suggested that you isolate all your audio connections, and try to seperate your MIDI cables from your audio cables.

I would suggest taking it one step further - power down each piece of equipment, one by one, and test until you no longer hear the hiss. That will help you determine which pieces of equipment are both causing and/or receiving the "hiss."

Regards,

SG.

[This message has been edited by sgosh (edited 12-22-2001).]