Summary: Let gets started a little background i have tried over 20 dedicated bass head iem's ranging from the well know Future Sonic Atrios to the lesser priced Skull candy 50/50. I know hardly should be able to compare the two but everyone's journey starts somewhere. Anyway it has to be said these are the best bass heavy iem i have heard to date hopefully this review will shed some light on why so lets get in to it.
Summary: I absolutely love these. They sound phenomenal. I recently got the m40x, and was a little scared that it might make me frown at the JVCs....but I'm happy to say that the m40x for home use, and the JVCs for travel is an awesome pairing. Bass is deeper with the buds, but the clarity that I enjoy with the m40x is definitely present and I enjoy both equally for the intended purposes.
Pros: Great fit (with sony hybrid tips)..Rich, deep bass...excellent clarity across the board
Summary: Disclaimer #1: In my experience, I've come to discover that the term basshead is tossed around very loosely, and (more often than not) carries a negative connotation, when that need not be the case. Where I'm concerned, such terms must be put into context. As I've used it here, the term basshead merely implies a listener who admires (and/or maybe even prefers) a moderate to heavy bass lift.
Pros: Alas! A basshead's IEM, brought justice!
Cons: Yet another Frankenstein-esque design, which I can live with, but can't say I prefer to.