Recording from a computer sound source back to a Cubase proj

(Newby alert)

I’m trying to create the sound-track for a short video. I have the voice-track laid down, and now need to add an FX track, comprising bell sounds, from a Bell simulation program - on the same computer as the Cubase (LE 5).

I’m presently feeding the computer output to an Alessis mixer, and have it set up so that I can hear the bell sounds on the monitor (“2 Trks USB to Main” is enabled, , and “Main to Monitor” is enabled)

I have a new project, with one stereo input, but can’t figure out how to link this to the sound output from the computer (bell simulator output).

In some ways, this problem makes sense - I don’t want to create a feed-back loop, but it seems to me that I should be able to assign the raw output from the computer to an input channel, and then have the two tracks from the recorder show up as different channels. I understand (if I am RTFM properly) that there are 10 channels of audio on the USB bus, and it seems to me that it should be possible to manage those channels to accomplish what I want to do.

However, as a newby, I’m quite prepared to be told that “Nope - doesn’t work that way!”. Which leaves me with the original question:

How can I get computer created sound out to my external mixer, and then back in to the Cubase Software, given that the mixer is ‘monopolizing’ all the bandwidth on the USB port?