The Altec 251's had problems overheating and the metal speaker stands would crack the bottom plastic. I worked in the Altec engineering dept for over 2 years and at one time had hired over 15 temps to take these apart, place plastic washers on the transformer screws so they wouldn't get as hot, then reassemble them. You can tell if you have one of these refurbished 251 units by looking on the bottom and see if there is a white mark from a white Sharpie type marker. These were sold as new and put back in original boxes. Not actually refurbished but updated if you want to call it that!!! The unit is ugly if you ask me and the specs are really nothing to write home about. The volume control chip tda8199 (3 pieces per unit)is rather noisy but it was cheap. I'd look elsewhere for a cheap 5.1.