I'm interested in owners' experiences matching their subwoofers with the main speakers. A few categories:
1) Everything went fine.
2) After matching levels at one SPL, you found that the levels were different at another SPL.
3) There's a problem with the crossover: phase, dips, peaks, etc.
4) There's a difference in timbre between the main speakers and the subwoofer: dynamics, distortion characteristics, decay, transient response, etc.
5) The subwoofer excited some room nodes that the main speakers never affected.
6) A few hundred other challenges that I haven't thought of.
Jan