Time for an upgrade. The following are my requirements. I'm curious what you guys think.
Budget - < $450
Source - Fiio E18 now (plus ODAC+O2 or Schiit stack in a few months).
Requirements for Isolation - Absolutely none.
Preferred Type of Headphone - Open air.
Preferred tonal balance - Fundamentally balanced, but also vibrant and exciting particularly in the mid-range. Not too much emphasis on bass.
Past headphones - Grado/Alessandro (they died but they were great), AKG K240, AKG K551, Beyerdyanmic T51i.
Preferred Music - Indie, acustic, pop, rock, and virtually everything else. I listen to a very wide range of music.
Candidates - So far I considered the Grado RS325e, HE-400, Mad Dog, and HD650. A friend of mine who is really into audio recommended cheap vintage orthodynamics (e.g., HP50, YH-100) and to save my money. I don't doubt that they sound great but I'm not sure about their soundstage and they are not so easy to source. I'm very open to other suggestions. I'm OK with buying used as well, if not too hard to find.
My current main headphones are the AKG551 which are plenty decent for closed back. However I'm looking for something much more exciting with excellent soundstage, that make you feel like the music is being played in your room, with clear distinction of where the individual instruments are located. Comfort is also very important. I don't care about looks or size as I'll be using them at home exclusively.
I realize that my current portable amp/dac combo limits me in terms of what it can drive. I'd be fine with headphones that are decent with the E18 but will shine when I get a better amp. I would not be okay with a pair that down right suck with my E18, as a few months could pass before I acquire a more powerful amp.
Thank you for you input.