Haven't heard the UM3X, but the SM3s are quite different from the W4, most notably in mids density and spatial presentation. Vocals are more dense and forward than on the W4, yet the SM3's unique presentation still conveys a good sense of spaciousness, just not forward projected, but rather surrounding you. You may end up loving or hating it, but they're at least different enough to give them a try.
how would you best describe the vocals? i'm a bit concern because i use an ipod classic only as my main dap and it is a dark sounding dap so I thought maybe the sm3s would or would not have a good synergy with them and may result in a very thick mids? on the w4 it's already enough and doesn't take away everything.. on the um3x, still surprised very forward yet clear and detailed never sounding thick ..
does the sm3s also get your attention to its details like on the w4 that you said on your review on them?
as far as i remember way back august when I auditioned the sm3 (but did not pay much attention to it) i felt the mids are there like they're floating in front of me then the electric guitars are just there on the scene not as forward or focused like on the um3x and the highs, hmm.. it's there but never gets my attention only if i exert an effort..