I'm going to approach this from a different perspective...current. One of the critical design criteria of any amp, not just Class D, is not only how much power it can deliver, but most importantly, how much continuous current can it deliver at a particular voltage. Given that we're driving low impedance devices (i.e. speakers), current driving capabilities become very important, in fact more important IMO than how much voltage it can swing. Any amp can swing voltage, but it's the current it can deliver at these voltages which will ultimately determine the performance of that particular amp. I believe many of the things we're describing here with regards to "slam" has more to do with the current driving capabilities of the amp than the so-called power ratings itself. In fact, when an amp's clip light typically illuminates, it tells you it's max voltage swing has been reached (Voltage clip), but very seldom, if at all, does it tell you that it ran out of current while driving the speaker load based on the voltage its putting out across the speaker terminals, even if that voltage is still within its power rails. This current capability primarily is determined by how well the power supply is designed. But in class D amps, another consideration which has to be taken into account is how much continuous power can its output handle before burning up the output filters necessary to filter out the PWM artifacts inherent in the Class D technology. Typically for the better Class D designs its 1/8 continuous power, whereas in a good linear amp (Class A/B, H), it can deliver its full output power continuously, all day long.
The PLX2402 was mentioned in this thread in a non flattering way, and I agree 100% While it is probably not the PC thing for me to say (not that that has ever stopped me! ;-}), I have dubbed the entire PLX series as the POS series. It was QSC's first attempt, I believe, at a SMPS to lower amp weight and it was the big "fail" IMO, regardless of what one QSC employee/TB member here tried to explain away here as gain matching. I had one new in a box in my shop for the longest time and couldn't understand why so many players where bridging this amp to get even close to the capabilities of our then HT322 cab. I finally took it out of the box, plugged it in, and was horrified! Even next to their 300watt @ 4ohm amp it was "no contest". The more I turned the PLX2402 up, the harsher and worse it sounded. Sure it was louder, but it lost all the warmth and yes, "slam", you would expect from such a "powerful" amp. In fact, trying to eq more bass in only made it worse because it caused it to drain its current capabilities even quicker. Back in the box it went, and I honestly don't even remember what I did with it. Maybe I left it behind when I moved ;-}
