Roy,
After un-installing and re-installing Indigo-DJ software I am now able to use the Indigo-DJ hardware and hear sound from a YouTube clip, played directly from the YouTube website, that is, using the sound system I have for "performance" karaoke configuration (amp, speakers, etc.).
The humming noise was corrected by replacing an incompatible power supply.
My remaining problem is that I can not hear any Hoster audio via my sound system used for performance karaoke. (Video appears to be fine.) Additionally, YouTube clips can not be heard via built-in PC speakers unless I remove the Indigo-DJ hardware from the PCMCIA slot.
I have attached all the set-up information I think might aid in troubleshooting this issue. My hope is that I do not have to abandon this effort and purchase another laptop to use for this single support need (that is, "back-up" Karaoke/Juke Box).
As always, any and all help greatly appreciated!
Best,
Gwen