I decided I do not need to wait a day or 2 to form my opinion of the SM64's. They are flat out awesome and I do not intend on trying out other IEMs at this point.
Bass: After owning the JVC FXZ200's I didn't think bass could get better but it does with the SM64s. It's not that the SM64s have more bass but the quality exceeds all other IEMs I have tried. Sub-bass in particular is muscular and appropriate. At times I got the sensation of a subwoofer playing in the room.
Mids: The mids are see-thru quality, smooth as hell and extremely life-like. So far I have listened to the Carpenters, Stevie Ray Vaughn, Patricia Barber, Led Zeppelin and Wilson Pickett. I have not heard all of them presented so perfectly natural in a sound stage that is so unlike an IEM. In comparison, the X10, TF10, FXZ200s and IE7s sound so fake and artificial.
Highs: This is where I am a bit surprised. I was expecting the SM64s to be a tad bit bright but if anything they sound a bit tame on top until you realize that all the treble details are there. Highs are presented so naturally it initially fools you into thinking they are not very present.
Sound stage: Just perfect. I can place instrument locations easily and hear studio wall boundaries when present in the recording. Vocals do not feel like they are squashed inside your brain as they do with the 200's. The SM64s offer a 2nd row perspective.
Fit and comfort: I am not used to using over the ear wires with IEMs so it took a bit of practice to get the fit right but once in place they stayed and fit perfectly. The double-flange tips that come already mounted offer great isolation and to my ears fit like a glove.
As far as amping is concerned, the volume level coming out of my iPod Classic is just barely enough at the max setting to provide comfortable levels for most music but is not quite enough for all. I think a portable amp is helpful with the SM64s.
I think I got very lucky. I found a perfectly balanced IEM that has all the sonic attributes I was looking for and value and has exceeded my expectations on all fronts. The search has ended for me.
Edited by RatFarm - 2/19/13 at 5:13pm