Holy Shure

Just got my 535s and I am so impressed. Never thought I'd like the Shure sound after I tried the e4c because of the thin bass but these things kick. What is the most similar custom?

how far apart in the bass department?

UM2

Least bass of the group. But ok on quality. Overall bass is thin and lacks presence. However, it goes quite deep and is articulate. At lowe volumes, bass is even less present. I was not a fan of the bass on these as it lacked in quantity. Compared to the SE535, the UM2 is has less bass quantity and quality. There is really no comparison as the SE535 has plenty of bass and it is articulate and textured. 

W4

Bass is there at higher volumes, but still less presence than in the 535s. At low volumes, bass is hard to decipher, especially deep bass. Bass on the W4s is tigher, much like a 8-10 inch woofer, whereas the bass on the 535s is like a 12 inch woofer. Bass on W4s is articulate, but not so articulate in the lower ranges. I found it to have tight and articulate bass most noticeable in the upper range, but found the deep bass to be lacking in presence. SE535 has more deep bass, the deep bass is much more defined, but the upper bass is about the same as on the W4s. 535 has a fuller and wider bass range.

IE7

This is a tough one. The bass is hard to pick out on these since the mids are so strong. The bass is bloated at times and lacks a lot in detail. There is a lot of it, it is just not well-presented and when it is there, it drowns details out. However, the upper bass and lower mid range on these is really quite pleasant and articulate. I would say that the upper bass and lower mid range is the defining quality of these. Compared to the SE535s, there is much less deep bass in the IE7s, and bass overall is less articulate in the IE7s.

@gilly87 BTW the CX300s that you have are not much different than the IE7s. The bass on the 7s is a little less present and a little more detailed, but that's about it.