I have used a couple of these for many years, in and out of cars, indoors and outdoors in changing temperatures and they have never failed me (until recently, when I lost one channel, but I suspect it was my fault). I have used one to power a pair of HK PREMIUM PRO 18 subs, and the sound is nice and thumping. The other one I use for 2 or 4 JBL tops, and the sound is very clear and crispy. I took one of them to my local serviceman a few months ago, and upon opening it, we found that the design is not the best. Access to the printcards is difficult (and repair costs consequently too high), so it looks like the best option is to buy a new one.