How do USB Audio Inerfaces work along with soundcards?

[Grunwaldt]

Hi all,

Excusse my noobyness and poor English (Also I don't know if this forum is the one properly for this kind of questions)

I have a Xonar DX sound card installed. My problem is that I need 2 line-ins for my KORG synth and guitar fx processor, which my current sound card lacks of.

I'm confussed about how USB Audio Interfaces work, do they act as complete sound cards? I don't want that, because what I need is just line-in's that sound through my soundcard at the end, using the Xonar soundcard.

I've been searching the web for these devices (USB Audio Interfaces), but can't find if the sound is routed to the existing soundcard hardware at the end.

I've been considering buying this one:

http://www.rolandus.com/products/produc ... uctId=1155

I will apreciate greatly if anyone could solve my doubt!

Also *IF* USB Audio Interfaces aren't what I need, how do I achieve more audio inputs? what kind of hardware would I need?

Thanks, any advice is welcome!

[audiohead]

I think you just need a small audio mixer. Behringer makes cheap ones, like this one:
EURORACK UB502
But you can definitly spend more money, if you want.
You should take care of good preamps and low noise.

The output of the mixer goes to your soundcard. That's it.

[vim]

If you were to use the PRO version of FutureDecks, you can then use a USB Audio Interface that has inputs and then you route the audio back to the soundcard's output.
Did I mention we have a very good upgrade offer?