I have only heard the standard Pod items that came with my Classic and the CX95s which I bought on reputation.

They were very nice about it when I asked for my money back and said they would let me know if my CX95s had a fault.

The best bit about them was the midrange accuracy which blew away the Apple item. Unfortunately, the top end sounded shrill and bass was lacking too.

Careful checking of the equalisation curve to ensure there was no maladjustment. Adjusting the curve bass heavy and treble light did help.

Either they were faulty (I have never heard back from Sennheiser so not sure) or they were a mismatch for my Classic. I never tried them on any other source because I wouldnt listen to a hifi source with earphones (headphones occasionally).

A friend who is a recording engineer, came to the same sonic conclusion.

I've also owned a pair of CX95's and was not that impressed.  As with most of the Sennheiser ear canal earphones the bass drowns out the mid frequencies (I've also owned CX300's).  I guess the very warm bass response appeals to most people - I'm sure Sennheiser have done their market research on that one.

I now own a pair of Shure SE520 ear canal earphones and have to say I can't fault them.  They sound absolutely beautful, with an incredible level of detail and plenty of bass if you want it.

Has anyone compared the Shure SE210 with the SE310?

You can get the SE310 for ~£110, cheaper than I can find the Jay q-Jay or the Etymotic so it would be good know where they would fit with the rest of the reviewed phones.