I have owned and played on one of these heads since the mid 80's. It's been bounced around in the back of a pickup, inside a trailer, and in the bottom of a bus. Since I live in North Dakota, it was stored in the cold and expected to perform within minutes of being set up at a gig. This is my favorite combination, the Mark IV with a Peavey 1810 (the original 1820 cab). I have also used it to power a pair of 15" subs, the complete monitor system or just as a bull amp in PA amplification. It's never let me down and I will never sell mine. If you're looking at buying one, how it was cared for will make the difference. While I expected alot out of mine, I took care of it and that's why it's running good today. If you have a picture, look at the knobs or the tolex covering. The first step in taking care of your electronic equipment would be to have a cover. This amp has heat ventilation on the very top and anything could drop into it. If it's been cared for and not abused this will perform and power many different applications.