[Roy Dennis]

It's a long time since I used XP but if you go to the Audio Tab, in that dialog, at the top you should see "Sound Playback" default device with a drop down arrow, clicking on the dropdown arrow should show your "Indigo DJ pcmcia card" (providing it is connected at the time) select that so that it shows in the default device panel then press OK.
Now go back to Hoster's audio controls and under playlist audio card use that drop down arrow and you should see your indigo card select that so that it shows in the playback audio card window then press OK.

Now your indigo card apparently has 2 outputs (or 8 virtual tracks) one for headphone and one for main mix, so when selecting the defaults playback devices it may show 2 devices or more for indigo in the dropdowns, you must select the same for the windows default as in Hoster's default.

If your sound card uses "Asio" drivers then you may have trouble using it with Hoster as I tried that type at one time and could not get them to work right with Hoster.
Perhaps others can advise on this.

In your original post you stated "while I am able to get YouTube clips to play just fine I am not having any success with Hoster sound"

Do you mean your not getting any sound from any karaoke files or just the YouTube videos ?
If it's just the videos then it could be a Codec problem you need to install the K-Lite codec pac.

Do you mean your playing you tube clips through Hoster ?

If so are they downloaded first or streamed direct from Youtube ?

Only I have only ever been able to play Youtube clips by downloading file first.

Let us know if the above helps.