Last week I used my SL1 interface as a USB audio device at a show with my band Fosforo.
The SL1 has two sets of stereo outs and two sets of stereo ins. All i/o is RCA and the audio quality is 44.1k 16bit so it's very basic and it does the job well using a basic ASIO driver.
I hooked up the SL1 to my laptop (Gateway 400 series with P4 2.2ghz proc and 768mb of ram) and I've been using a very useful free VST host called Cantabile light. Nice thing is you can load a VSTi and a VST effect and you have instant combinations...the full version I believe allows for multiple combinations. Software also can record Midi data from your controller.
The only issue I ran into was setting the samples correct in order to reduce latency and an annoying clicking sound that surfaced while at sound check using another popular host. I also had midi stuckness and restarted the host in order to refresh my VSTi's.
From the SL1 (mono signal from Left output 1) I took an RCA to 1/4 cable and placed it into the passive input of a Trace Elliot bass head with a XLR DI output. It's also the first time I used the effects loop as well with an Ibanez delay. It all worked out nice.