[ScottK]

I'm in the process of changing job and am going to spend a lot of time in an office on my own over the next few months and I was looking for suggestions for some new kit.
 
My source will be a macbook pro (mainly ALAC files) and I can spend ~$500, to include a DAC/amp and some headphones.  Generally I listen to classical music, with some jazz as well.  Historically I have bought a lot of IEMs but given a move to an office, thought I should move to full-size.  When listening to music with more bass, I will always default to my Heir 5.0 IEMs so that shouldn't be a consideration here.
 
Initially I'm thinking of grado 325, but I really don't know the full size space well (I've got some HD598s at home, which sound great, but look dreadful).
 
All help appreciated.

 

[ns6490]

Eh...

 

[Galvatron]

I'm not sure I'm entirely qualified for this. But I picked up some V-MODA m-100's, easily puts itself in terms of sound quality with headphones in the 400+ range in my opinion. It has a little more of a focus in the lows & mids but the highs are are vivid and aren't tinny or limited at all. 
 
I also would recommend the Audio Technica

 ATH-ESW9A's they're pretty affordable high-fidelity audiophile headphones. ​

 

It's not a bass-head pair of cans but it equally destroys and range of music you listen too. ( To put it in a better way it sounds breathtaking in all spectrums of music)​

 
In terms of amps, for the V-MODA M-100's it's really up to your own taste I wouldn't say much is needed. I used a few different amps and all it did was make the treble louder (Which I'm not saying isn't an improvement but it wasn't an overall noticeable upgrade)
 
for the ATH-ESW9A's, Audio Technica prides themselves in not using amps for their headphones these things are fine on it's own.
 
I must say Im not the most experienced person with amps but I do own a few and even then I don't use it that much.
 
Hope this was somewhat helpful these headphones are in fact the ones I own and love them both.

 

[Snowdog57]

Given that you'll be listening to classical, I'd go with Schiit's Magni/Modi combo, without hesitation, first. That'll leave you with 300 clams to snag-up some pretty decent cans. Good luck with your search!