This forum is a great resource. Thanks in advance for all advice. I am looking to upgrade my headphones. I currently have a Grado SR60 set, and find that I like the "spaciousness" of the open-back sound. However, I find them fairly uncomfortable. Within my budget range on the local second-hand market, I am looking at the Sennheiser HD598, AKG Q701, or possibly the Beyerdynamic DT880. Given that (a) I listen primarily to classical and jazz, (b) I would like to avoid using a separate headphone amp, and (c) I need the headphones to be very comfortable, is there anything to specifically recommend one of these sets of headphones vs. another? Are there other models that I should be looking at as well?