LinuxMusicians

So I'm really a bit new to the whole sound recording thing, I have a guitar going into a line6 amp and I then bought an alesis multimix4 after reading reviews on here figuring that I could do analog out recording to my Boss MicroBR 80 and also digital to a linux box if I wanted. Now recording to the BR80 works great, so already I'm pleased, and just to see if it worked I decided to try recording directly to one of my Linux boxes. The device is recognised fine, no issues there and I figured the easiest thing to try is my old friend audacity. Audacity recognises the devcie and hitting record just works, however there is a lot of distortion on a clean sound from the guitar amp which I guess means the audio is clipping and this confuses me as there are no clip lights coming on on the multimix. I've tried turning the main out way down on the mixer (and also all the way up so that I can see the volume level lights don't go into the yellow or red), I've tried adjusting the volume on the pcm out for the usb sound card in alsamixer but that doesn't seem to do anything, any suggestions?