Re: E-drums , stage monitors, and low end build up in FOH
One downfall of Aux Fed Subs is that varying the level of the sub send will effectively change the acoustical crossover, thereby changing your alignment. It might be a better compromise to lower the sub send and throw off the alignment a bit to keep the bass under control, but that would be something you'd have to determine for yourself. I know I've done it, even though it goes against my 'alignment sense'. It also depends how good the alignment is - if you're pretty much exactly phase-matched for several octaves on either side of the acoustical crossover (this rarely happens, but one octave is pretty usual), then varying the sub send level may not be detrimental at all.
Also, remember that perfect alignment can only be had for a very small portion of a room, the rest is already a compromise. I'm also doubting that many people actually go through the same thought process I do every time I enter a venue or a situation just like this, since I'm probably just adding complexity to a show that doesn't really require everything to be absolutely perfect.
I guess it all comes down to, 'If it sounds good, it is good'.
Apologies for the stream-of-consciousness post.
