Complicated subject, because it involves elements of hearing perception, as well as the technical capabilities of the KSC75.
My thoughts...
They do get a lot of hype, and for $15 they are a great bargain. I find them much better and more enjoyable than the stock apple buds I demo'd at Headfest. Personally I don't find burn-in to make much difference with the KSC75, but then again, they are not my critical-listening phones (so take that with a grain of salt). Amplification and source does make a difference. However a vintage $20 PCDP and well-designed, $40 cmoy will trounce any unamped MP3 player I have heard. So hi-fi does not have to be hi-$$$. make sure you have a good snug fit. If they are loose and just kind of "cling" to your ears, you will loose much of the bass impact.
A lot of it depends on your hearing perception and personal preferences. If you prefer boosted midbass, rolled off highs and sub bass that doesn't extend very deep the apple buds will certainly deliver that kind of sound, and they'll do it better than just about any other stock buds I have heard. The vast majority of apple users prefer the sound if the iBuds, so Apple certainly did their homework, when researching what the
typical (non head-fi) consumer wants to hear.
I found the ibuds a bit congested. So, IMHO the KSC75 is capable of revealing a little more detail, but in a noisy portable environment that difference can be harder to detect.
Its not uncommon for new members (with un-trained ears) to be underwhelmed by what they hear. It takes some prior experience to know "what" to listen for in each track. I let my non-audiophile niece demo my Grado setup, and compared to my KSC75... she couldn't detect a difference
. It wasn't till I TOLD her what to listen for in each tune/track that she went... "Aaaah... NOW I hear it".
How loud do you listen to your music? I find that my hearing perception drops dramatically the louder I listen to the music. At loud volumes, everything kind of compresses together and the finite differences in sound become lost.
I say, give it some time, let your ears acclimate to the sound. Listen to them in both noisy and quiet environments, at loud and quiet volumes too.
Its also possible that the individual
tracks of music you listen too are not capable of revealing the differences.
My advice to you is to just kick back and enjoy the tunes... Forget about what you aren't missing, and groove to the music. In the end, thats what this hobby is all about.