In terms of technical capabilities, the SE215 is a step or two higher VS the Klipsch Image S4/S4i IMO. The sonic coherency of the S4 isn't on the same level compared to the SE215.

The SE215 has better soundstage and spatial layering VS the S4, and I'm gonna go on a limb here as I've neither of them for a very long time, but the SE215 feels that is has better spatial positioning VS the S4 as well (never gamed with either, so I can't judge this part with concrete confidence).

Soundstage felt larger on the SE215 and with the proper spatial layering applied, it complements the soundstage of the SE215 better VS the S4.

The SE215 has a more prominent bass region VS the S4, but the S4 hits harder. Comparing the midrange, the S4 feels dry and recessed whereas the SE215 feels more natural in this regard. The S4 has far greater treble energy compared to the treble regions of the SE215, but both earphones have a bit of a grainy upper midrange / lower treble region.

For the record, I found the SE215 to be more comfortable compared to the S4 as well.

Contributor - End user and owner of both products.