Most of the recommendations for SVS or Hsu were for home theater, where those subs tended to go deeper than the smaller Axiom subs. For music, I don't think that is really an issue.

Based on the reviews I have seen, I think the EP125 would be fine. I went with a larger sub for my M2s but IMO the real benefit was movies not music.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8