I currently have ad700's with a xonar stx soundcard, and I was looking for a decent upgrade.
I love the ad700's alot, they work for what I like, so would the ad900's be a worthwhile upgrade?
any other suggestions are welcome.
The ATH-AD900s should sound better then the ATH-AD700, but you may not see a big difference.
Personally I would go for the Beyerdynamic DT990 Pro 250-Ohm, lots of bass.
I really just love the clarity on the ad700's, and I'm assuming the ad900's are even more clear. Bass isn't really a big deal for me but it couldn't hurt. I've almost forgotten what bass is like now that I've been using these for about a year.
A lot of the Audio Technica headphones we have been talking about are usually around 40-Ohms.
I think my O2 amplifier is a little better at driving Audio Technica 40-Ohm headphones then the Essence STX.
Kind of why I'm pushing high Ohm headphones for use with the Essence STX.
If you get the DT990s (250-Ohm), you can always keep the ATH-AD700s around for when you want easy listening.
The Audio Technica ATH-A900X are really one of my nicest sounding headphones, but sell new for around $250.
If you watch eBay and Head-fi "Headphones for Sale" thread, you might be able to get a used A900X for around $185.
Also the Fischer Audio FA-011 (160-Ohm) seems to be well like, sometimes sell used for around $110.