I think I've posted this before, but I am very anti-enhancements generally. I don't use EQ, I don't like tone controls, and I never use any of the DSP options on processors. So for me to be this much in love with the crossfeed circuit, that's really very unexpected. And of all my phones, the ones it works the best with are the T1s. If I were Jan, I'd develop a crossfeed buffer, of sorts, and market it as a stand alone product. It would sell like hotcakes!
TBIsone set on minimal crossfeed (it is a preset) is my solution with T1's. Locks it in with a perfect soundstage and adds no coloration. I use this in JRiver since it is transparent with plugins. Works so well I bet it is similar results to those you are getting with your amp crossfeed.