Can you throw some recommendations my way?

Hello again. I’ve haven’t been in the market for headphones for a while, mainly because my wallet hates me, so I'm not up on the latest models, but I may start looking around again. I gave up on IEMs because they irritate my ear canals, but most of the time I have to wear closed-design phones due to noisy neighbors. I quite like my HD280s for this purpose, but once in a while it would be great to break out some nice open-backed phones for a more realistic soundstage, maybe when the numbskulls upstairs are asleep.

Maybe you could point me toward a good choice for my needs….

• These open-backed phones would be mostly used for listening to classical music, plugged into low-powered sources like a computer audio jack. I don’t have a headphone amp.
• I prefer a relatively “flat” or uncolored sound signature. 
• Budget-wise, I’m probably stuck in the budget-fi to mid-fi range, however you care to define that.
• Comfortable, washable/replaceable pads would be a plus. 

I used the Sennheiser HD590s for years until they eventually fell apart. The 555-595 series might be an OK choice but they just a little “stuffy” to me. My next thought was to try the Audiotechnica ADxxx series -- I liked their closed-design equivalents a lot, but they developed a crack in one of the (rather delicate) earpiece holders, and I worry about that occurring again….

Any thoughts?

Thanks. If the Audiotechnicas can avoid breaking on me this time, I may go for them. Two questions:

1.Does the ADxxx series have replaceable pads?

2. Is there a huge sonic difference between the AD900 and the AD700, considering that my source is nothing fabulous?

My recollections there are mostly of the HD555s, which I had longer than the others. Stuffy as in very slightly veiled or rolled off on top, in what seems to be a nod to Sennheiser's traditional house sound (the HD280 being a notable exception).