[quote name='alexclaber' timestamp='1461361734' post='3034128']
It isn't, it's down to current delivery. A powerful SMPS will far outperform a less potent transformer+smoothing caps supply. Big bass notes need high current and sustained high voltage without sag for much longer than most Class D modules are designed for.
[/quote]Not quite true Alex. Most class D amplifiers are designed for high power in a compact footprint. However adding more heatsinking or fans allows you to achieve the full performance. Take for example the TH500. On its own, the ICEPower module used by Aguilar, rated at 500W, would probably only achieve 25% of that. However Aguilar add two fans and this allows the module to give everything. For home use the heat management is fine. For professional use you need more heat management. Once heat management is correct then the limiting factor is the power supply.
So if you see a 1000W amp in a box the size of a small box of chocolates, walk away. If you have an old SVT, you can't walk away.