Over the past couple months I've had a bit of a headphone/IEM obsession, which has lead me to purchase some great, but mostly not so great, headphones.
Recently however I've acquired a couple of pieces of equipment that have thoroughly impressed me with their quality:
Fiio E-17 Alpen headphone amplifier/DAC
This little thing-- it's about 2/3rds the size of my iPhone -- is absolutely amazing and has opened up a world of audio fidelity that I have yet two experience with a pair of headphones. it has a variable gain switch; bass, treble, and balance controls; can accept input from just about anything you can imagine: USB, SPDIF, Optical etc.. Via a 13 pin line out dock, the digital signal circumvents the iPhones subpar internal amplifier and digital to audio converter and routes the unamplified signal directly to the e17. It has turned my iphone into a veritable audiophile device.
I have it attached to my iPhone case with velcro, like so:
I also purchased, after extensive research a pair of Thinksound TS02 earphones:
For $80 the sound quality of these IEMs is immense. Nearly perfect balance across the frequency ban, (admittedly they could use a bit more sub bass extension), and the soundstage, width and depth are absolutely stellar. In my opinion they are the closest you can come to perfect audio fidelity for under $100, and the synergy between them and my headphone amp is nearly perfect. And did I mention they are made from /packaged with recycled materials. Their customer service, from all the reviews I've read, is second to none, although I've not yet had to take advantage of it.
I highly recommend both products. Together they have, for me, opened up a whole new world of music appreciation.