Re: NAD tommorrow! Question......
The Maxon ST-9 Pro Plus (Super Tube) is a great pedal that I believe you should look into. For me it has two functions. (1) Great blues tone on a clean channel. It really sings! (2) It's also an AWESOME OD/Boost pedal to augment a high gain amp (which is what I use it for)... it gives me deadly definition with my high gain amp channels. I suppose my second point doesn't really pertain to this particular amp. So that was a useless statement. lol
But if you're looking for a straight distortion pedal to go with a clean channel, I'd suggest looking into the Maxon SM-9 Pro Plus (Super Metal). In my humble opinion, it's better than any Boss, Digitech, Jeckle & Hyde, etc. distortion pedal I've ever tried.
Maxon pedals are fairly expensive (especially the newer pedals), but I think they're worth every penny. I got my first one about two months ago, and I'm hella glad that I did. Great products!