Hi there, I just picked up an M-Audio ProFire 610 firewire audio interface today. A local shop was having a big sale, and these were going for $300 Canadian, which sounded like a great deal and I've been on the market for such an interface for a few months, so I went for it. Its my first time using an audio interface, so while things aren't working out as I expected, I"m not sure whether the product is defective or if I'm just not understanding things correctly, so I thought maybe somebody else on here who might have experience with the hardware might have a suggestion. Basically, I think the problem is that the gain nobs for the two input channels on the front of the unit don't seem to work at all. I can plug a guitar into either channel 1 or 2, and I can measure the sound level on the visual mixer in the Control Panel software, and the sound level doesn't change at all, regardless of whether the gain nob is turned all the way up or all the way down. I tried this while recording into garageband too. I was able to set up the inputs alright, and I could get a fairly faint recording, but the level of this recording wasn't at all affected by my turning the gain nob for that channel. I've made sure to download the latest driver off the m-audio website for my OS (10.4.11). Its a 2.2GHz SR MBP. Something tells me this isn't software related anyways, because I've tried testing this as a standalone, using external power and not connecting Firewire, and just monitoring through the headphones, and I still don't get much of a signal at all, even with all the nobs cranked to max. So does this sound like a defective unit to you? Or is there still a chance I've missed some critical step? Thanks a lot for your input. My plan is to head back to the store tomorrow, but I thought its worth looking around online a bit first, though I haven't found much out there on this unit. Thanks!