Another benefit of using a subwoofer amp (often done as 'plate amps'), and the very first reason I used mine (aside from beying ICE design, well working/sounding, powerful): The amp came with adjustable crossover frequency and volume control (unlike my other existing 'power amps'). So using it was a given; putting it NOT into the tight space (sealed) box of the sub was just gravy (more usable volume for given exterior dimensions) AND easier to acomplish.
But I guess the adjustable crossover frequency is also part of most receivers; in my case, I need to select 'small' speaker first, then I can select high pass and low pass frequencies.