I've been doing a lot of research, but all of the information I've ran into is conflicting.   I am looking to buy a amp and DAC for my Audio Technica ATH AD900X.   Firstly, I am wondering whether this headset would benefit from an amp/dac or soundcard? Currently, the onboard Realtek ALC892...

Its overwhelming. I have no idea what to get.  Here are some of the things I am looking for:   -decent noise isolation (perhaps noise cancellation, Audio-Technica ATHANC7 in mind) -should be able to fold for portability -over/or on ear -will be used on public transit, so no open headphones...