I've had cascade/th900/lcd-2c and I think you would be disappointed with audeze. It has tremendous subbass but it does not have boosted midbass like cascade/th900. It's very different. Have you tried removing the white filter on cascades? It will open up the sound quite a bit. Upper midrange and highs will be more in line with the bass. You do sacrifice some of the low bass in process. Here is a measurement about the differences between stock and no filter.
Cascade and Audeze LCD-2c. I think bass on Audeze rolls of too much in my measurement but you get the idea. It's linear bass not boosted.
To me Cascades are not claustrophobic among other closed back headphones, quite the contrary actually. That sets bar quite high for a open back alternative. There is Sivga Phoenix, it doesn't have the bass tactility of the cascade/th900. Bass is boosted without going overboard and it is very well extended. Very rare on a open back headphone. Still not as bassy as Cascade though. Unfortunaly it is not as open as the design would make it seem. Soundstage is smaller than on Cascade but might sound more open, that is something only you can decide with your own ears. You propably could audition it in Singapore somewhere.
Have you tried TH900/other fostex headphones/old denons? They're quite open for a closed headphone. More so than cascades. They're worth a audition.
I can't comment on Aeolus as I have not heard them. It might be too balanced (not bassboosted enough) after cascades, but I could be wrong.
Other options:
- Klipsch HP3: I have not heard these either but they are very much like fostex headphones but semi-open
- Fostex TH909: Open TH900
- Philips X2 & Beyerdynamic DT990: Overall soundquality is a step back from Cascades and lack of subbass might be a problem. Theyre cheap so thats a plus.
- Sash Tres Closed: This is not a open headphone (it can though as it's originally open and closed cups are an accessory). I'm mentioning this because as a open version it sounds very spacious, airy and open and it has very similar frequency response to Cascades without white filter.
- Buy some Fostex/Denon headphones and take the cups off. Some people have experimented with this. There is some info available if you look for it. I have no experience with this but supposedly it maintains the bass or even increases it. You could grab used d2000 for cheap and try it yourself. If you like it maybe do it with some more expensive model later.