Every now and then I have to harp on about the Koss KSC75's. Here is an excellent post about them (even contains a shoutout to dsnuts!), and this is an excerpt:
My point is, I've spent thousands of dollars and thousands of hours in work and research into audio to try to create an audio experience better than a $15-20 pair of Koss KSC75's. As a overall package, i have never been able to achieve that. Of course this is subjective, i guess the frequency response of the KSC75's just sound pleasing to me. Not to mention it doesn't have all of the above problems of speakers and more.
What I've come to understand after approximately 4+ years to finding audio nirvana is that there is no perfect way to engineer a speaker/iem/headphone. Audio engineering is all about trade offs.
You're free to spend all the money you want to find better finding audio equipment. All i ask is that you at least give the KSC 75's a try before buying more expensive equipment. You may find no improvement, or too little to not justify a nice refund.
I've got the ksc75's on now. Hrmph.. X1's.. who needs them? Not me!!! (wow - awesome summoning of resistance there Wayne!)