About 2 year ago I decided to start doing outdoor park concerts with some friends in our church, I would purchase the sound equipment and they being musicians would play or find others to join in. We started small, a few 15" two-way cabinets, a couple of dual 18" subs and of course the allmighty power amplifier to drive them. Initially our budget was zip, funding all out of my pocket, and no we did not charge for concerts, they were free. In reviewing many of the power amplifiers specifications (QSC, MACKIE, BEHRINGER, EV, CROWN) we settled on a copy-cat type amplifier off a well know pro-audio manufacturer. The specs all appeared similar (close but not exact) so we opted to purchase a few to see how they would perform. Initially we fired them up and they ran well for our first venue. We have 8 mains, 4 each side and a couple of double 18 subs along with a few single 18's as well. The system was not pushed too hard since we were covering a small area. As time progressed so did our system. We ended up with 17 of the copy-cat amps in 1500 and 2400 watt versions, supplying power in bridged mono and stereo modes of operation. The manufacturer states in their sales literature that the amps can go all night and take a pounding and still produce quality sound. This just ain't so. We found that as we grew and the venues got larger pushing the amps caused them to clip and shut down, distort and loose the punch we were seeking. We did by this time have a few of the real deal amps these were copied from, and found they too were better than the copies, but still lacking the punch we were seeking. This is when we started to really look at the specs as well as the power supplies, damping factors, abilities to run in bridged mode, distortion levels in bridged etc. We quickly found that the specs of the copy-cat amps, even though looked good on paper, were not what we were seeking and that the amps we were using were never going to provide the punch we desired. One thing we found as with the speakon type connectors we wrote a review on, you get what you pay for or what you can afford. We used RMX amps, tried some CARVIN units, dreamed about MACROTECH's and found a fit for us in quality and budget. The specs looked good. Damping factor was good, distortion and frequency response better than we were use to. We settled on PLX amps from QSC and found all of them right here on Ebay. The less expensive amps seem to use a torroidal transformer for power. We opened up the RMX, MACKIE, CARVIN and copy-cat amps to look at the electronics and power supplies for each. Most if not all of the weight of these amps is in the transformer, without that, not much to them. The manner in which they were cooled varied as well, which is real important if you are driving hard in 4 ohm bridged mode or heaven forbid 2 ohm mode. The more expensive amps appear to have better components, circuit boards, and overall manufacturing quality. When we upgraded to the PLX amps and fired up the system for the first time, they brought big smiles to our faces. Sonic quality was markedly better along with that punch we were looking for. One other notable issue we found was the power supplies to ALL of these amps is critical. We have 7 power amps in our racks. 3 running 1600 watts each in bridge mono, 3 running 2400 watts in bridged mono and one 3400 watt running bridged mono. With that being said, the nominal current draw for this rack is about 40 amps of power, that rating is not pushing that amp hard at all, with higher levels and push, the current (amps) requirements really go up. Don't think you are going to run a couple of amps from a 20A wall socket with good results. We finally had to go with a small electrical panel in each rack fed by a 50A connector and cable assembly with 2 50A single phases to each main rack, along with a custom power distro. Even though our budget could not afford the better amps up front, I do wish someone could have explained this to us before we wasted the $$$ on the lesser amps, maybe just getting the better amps and phasing them in over time would have been the ticket...after using these amps, the only place to go now is to the PL series or equal CROWN or holy moly, Lab Gruppens, now there is an amp!