Question for sub woofer users

I’m in the 2 subs are better than 1 camp myself. A pair of Ohm MicroSubwoofer 10’s have been in my system now for a few years and have been integrated easily (by ear) with 3 different pairs of speakers (Maggie MMG, Mark & Daniel Ruby, and Ohm MicroWalsh Tall). For crossover duties I use an old Outlaw Audio ICBM -1.

@jzzmusician .. a y-splitter would do the trick.

Yes, two subs if you can, it will be more robust and spread out.  Even though we say that bass below  a certain frequency is not directional, you still feel where it comes from.

Pretty much set and forget.  There are variables in the engineering of recordings that will make them 'stand out' or 'recede', but that's kind of part and parcel of 'modern music', genre dependent...
Proper placement....'sizing' or 'scaling', taking into account what you're pairing it with...room size....getting the crossover point 'right'...the usual variables we all know and deal with in any system...*G* 

Definitely get two subs.

One sub can be fine and you should simply move it around until you like the sound (generalizing, but my original REL worked great alone). I did get another REL last year and I like having two just to calm the corner standing waves. The "leave it alone" level thing doesn't work for me as bass levels on recordings can differ greatly, and I simply turn them up or down sometimes (rarely, but necessary)…no big deal as the level is right there. If you have a Room Correction Nanny gizmo you may be able to leave the sub level alone.