One of the things to know about the EP125v4 is you may need to get it out of the corners. That's really the case with all subs. Don't expect it to be as linear as the sealed subs. If you stick it in a corner, certain tunes may excite it along with your room. I don't know about the other ported Axiom subs. I can only tell you what I hear with what I have. There is no such effect with the sealed Axioms I have. If you stick them in the corner, you just get bigger sound - which some may or may not like.

I've only picked up a resonance on Fly Me to the Moon by Sinatra in the playlist I posted. No such resonance on the 500 or 800 in my main room or if I place the 500 in the same place as the 125 in my living room. No such resonance if I put the 125 in my main room. It's the 125/living room interaction that is exciting the mode in the 125. I've moved it out of the corner and all is well.

Recall what I had said about the active LFRs in my living room. It was the most amazing bass I ever heard. Just the active LFRs with no sub. They were better than 500s or 125s. So of course the room/speaker interaction really matters and the actives were made for my living room as far as bass is concerned.

Having said the above, other than the resonance due to corner placement in my room on that one song, I enjoy that song more on the 125 than the 500. Simply put, the dual 125v4 sound better in my living room than a single or dual 500. I just find it to be a very tuneful, articulate sub.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated