I built a subwoofer a couple years ago with two Shivas and a Mackie M1400i to power it. I have never had any problems with it and I haven't noticed distortion; hoewever... I am reading a book called "The Sound Reinforcment Handbook." It's about PA systems but much of it applies to hi-fi. It says that you shouldn't mix hi-fi and pro equipment together. It says that hi-fi line levels are much lower than pro line levels (hi-fi is between -16dBu and -10dBu and pro is around +4dBu). It also says that hi-fi outputs are meant to be terminated at a 10,000-ohm load and that pro audio inputs represent a 600-ohm load. Has anyone here experienced problems with mixing hi-fi and pro equipment?