I purchased a QSC3402 amp from Zybar. Zybar had the amp repaired. After a while, I noticed the second channel operating at a reduced capacity, so I sent the amp back. First, they never said the amp was out of warranty and were going to charge me for repairs. I ended up paying $100+ dollars for repair. Had I known I was going to be charged, I'd have fixed the thing myself. Second, they sent me an amp with the same serial number, but I think they sent me a completely different amp and just replaced the sticker with the serial number on it. Here's why: The fan on these models is incredibly loud. I spent hours figuring out which model of fan to purchase to decrease the sound yet provide the needed airflow. I ordered two of said fans and installed one of them (sadly, the second fan either came with a broken or I broke one of the blades). The new fan rocked and made the amp listenable. The replacement amp's fan is incredibly loud. While I haven't taken the amp apart yet to determine whether the fan is different, there's no way it couldn't be different -- as soon as I plugged the amp in, I was wondering from where all the noise came. The old fan produced no where near this amount of noise. The list of items changed did not include the fan, so I think they just took a completely different amp and put a new sticker on it. Why would they do this? I have no clue, but there is no way this is the same amp I sent them. Next week, I'll take the amp apart and see if the fan is the same. If not, then they sent me a different amp and just replaced the sticker with the serial number on it. Scum bags!