EXS 24 Logic Sampler Users Group

Hello,

I am having a ground hum problem with my Audiowerk 8 and Audiowerk 
cards.  We've lifted all grounds from all equipment with 3 prong 
adaptors, removed all other imputs from our Mackie 1604 VLZ Pro 
mixer, and have determined that the audio cards are causing the hum. 
We've tried different cables, swapped the Audiowerk 8 out for the 
Audiowerk 2, and the hum always comes from the sound cards.  When we 
disconnect the card's RCA cables from the mixer, the hum stops.

Has anybody had any similar experieinces with this problem?
Any suggestions, solutions.

Thanks,
David Benus