Hands down after owning just about every earbud devised by man except the (overpriced IMHO Yuin stuff) the Sony Ericsson hpm 62 with surgical tape over the back vent is still the leader of the pack.
NOT to be a thread crapper and for all the Monksters out there having fit issues or just fits in general. I give you the universal earbud silicone blob mod.
This is the Left side bud. As you can see it is a large blob of silicone strategically placed by bayesian analysis so that once put in the ear you press around until the bud is firing directly into your ear canal. A fairly large blob is used as you can see to take up the space and give enough material to support the housing for a good seal. Once done you will barely feel it there. Set your volume control down and away you go. I could make wild claims of SR009 rivaling perfomance and 3D renerings of the artist appearing magically in front of your eyes. I'd rather just have you folk who are interested try it out yourself and see what you come up with.
TheMaterial used here (yes I am actually nuts enough to put raw silicone in my ears) but thankfully you don't have to. Any drugstore or WalMart will have little packs of silicone putty used for swimmers earplugs. Usually in the 5 to ten buck range for a sleeve of 5 or 6 half inch blobs. About a third of one of those blobs is what you see up there.
Experience has proven that the clear stuff you see there is a little more dense so it provides a better seal, damps better, and takes the heat of the body better than the coloured variety you may find in some stores.
Yeah it effectively doubles the cost of the Monk, but look how much you save by getting the earbud equivalent of a Custom IEM