I've got a RCA -> 3.5mm cable and I plug my laptop into it. Works nicely but I did have to connect the shield of the cable to the empeg casing otherwise I got a really bad hum. Can't really do much from the laptop end so I had to do it at the empeg end. A ground loop isolator also worked but it attenuated the signal and it works just as well by grounding it. No problems so far but somebody tell me if I'm not supposed to do this!

- Trevor