Are you talking about a breakout box when you say
external sound card?

FYI there's a Hercules Game Theater at Ebay that's
at $20. Hercules Game Theater is a 3 piece rig:
soundcard, cable, breakout box and it runs the same
chipset and is comparable to the Santa Cruz. Hercules also
has an upscale device in it's dj series for mixing etc.
"in the field."

OTOH what you get with some of the higher end cards is
a cable with a number of pigtails on it for doing extensive
plugging and unplugging.

I found the link below yesterday. I gives an overview
of product. A bit pricey but it shows the kind of thing
available.

• Dolphin Music Soundcard selecter