I was actually surprisingly impressed with the bundled earphones, though i've no idea what you had with your S2 as the ones with mine were utter utter crap, just plain old cheap nasty in-ear (but not silicon bud type) things.
I wouldn't describe these with the S4 as tinny at all, if anything I would have said the bass was overpowering the rest of the sound :/
I wouldn't describe these with the S4 as tinny at all, if anything I would have said the bass was overpowering the rest of the sound :/