I know what you mean about the ‘No mud’
Never been able to do it properly by ear myself.
Seems like a powerful setup!
I do it by getting down on my knees next to the driver with my ears. I quickly rotate the phase from one extreme to the other extreme, side to side. As I move the control I listen for a peak in output from the driver. Once I find the peak, I slowly move the control left right over the peak until it syncs with the other subs. You'll know it when you hear it; its much like zero beating a CW tone (ham radio operations with morse code signals). When is syncs, you have a very defined peak with much tighter bass tones, no MUD! It's pronounced when you hear it. Give it a try; with a little practice you'll find it works very easily.
I can phase the subs pretty quickly and it makes a huge difference! I never liked the more standard phase controls you see with 0 and 180 or maybe some in the middle settings. The variable phase is absolutely critical as it dials it in vs. just getting it sort of close. If you move the control very slightly off of 'in phase' it turns to mud fast. You need to really dial it in; but once you hit it, its perfect.
