Everything IMO!
HD-650 + Zu Mobius- Does most everything right. Only lacks the attack & PRAT of the RS-1
RS-1- Ultimate headphone when I'm in the mood for it. Does justice to most genres, including most classical.
RS-2- Very good sound, and the darkest non-Alessandro Grado. Good bass, and more accurate note decay than the RS-1.
SR-325i- Rock only can IMO. Far to bright for most classical & some jazz. Does sound most excellent with older rock recordings, really brings out the detail! Heavy.
Etymotic ER-4P- Most neutral "headphone" ever (I have yet to hear a HP series Grado or any electrostats). Sounds very flat and detailed.
HD-600/580- Great for the price, but are both lacking something that the HD-650 has. I'll call it mojo
Alessandro MS-2- Amazing sound, but not enough bass presence.
Modded DT-770- Extremely thumping loud bass, but the sucked out mids ruined it for me.
Alessandro MS-1- Always my favorite pick in the <$100 bracket. Very fun sound, never fatiguing.
Ultrasone HFI-650- Great sound, bad build quality. Creaky & uncomfortable. "S-Logic" soundstage enhancer must not have been working right, soundstage/positioning less than others in the pricerange.
Grado SR-80- Bright, yet fun as heck to listen to. Gets fatiguing quickly.
Sennheiser HD-570- My first "high end" headphone. Sounded ok, but extremely hard to drive. Very comfortable & great with games!
Bose Triport- Gets bashed way too much around here. Sure, the build quality is lacking & they are overpriced, but they do not sound offensive at all. It's actually my favorite semi-closed can for around ~$100 (Ebay price
)
Audio Technica A-500- Didn't do it for me. Good soundstage, but not enough detail and the bass seemed weird. I didn't keep them long enough for a better impression..
Sharp MD-33- My favorite cheap isolating earbud. Sounds good, yet metallic & has an extremely annoying cable.
Sennheiser PX-100- Good comfortable portable can, but a tad too bassy & too expensive considering the amazing Koss KSC series.
Koss KSC-75- Great sound for the price! Better than the 35, and sounds even better amped.
Koss KSC-35- Like the 75, but with more bass & a tad less detail.
Sony Streetstyle- Crap, but they are what I listened to for maaany years.
Zalman 5.1 "Surround sound"- Sound absolutely horrible (no bass!!!), and do not offer better soundstage than say, a A-500 or HD-570.