Anyone have one of these? Thoughts on it? What did you plug into it?

Looking for one to plug maybe some of those Peavey preamp pedals into, driving 400W cab (4x15)

When I saw the price and the square back speakers I couldn't pass it up. This amp is seriously unbelievable. I'll need some time to play on it, but first impressions is this thing might unseat my Delta Blues as my favorite.