Woot, they arrived! I don't think I ever had to work so hard to spend $74.
I have them on now, driven by the Burson. Comparing to the HD650 is REALLY interesting. They definitely have some midrange resonance in particular to calm down, and the top end is, well, dull compared to the 650.
But here's the really interesting part, they sound ridiculously good for their price, and not only that, as many have noted, there's a real naturalness to the tone. They simply sound more real, especially with vocals. The HD650 has markedly more grain, and a noticeably bigger soundstage, but on first impressions the question is is the HD650 revealing grain in the source, or adding it? The t50 definitely is less bright, but it feels more natural up top, so this may be a reduction in coloration and higher-order distortion.
I will probably let these burn in before I tweek, as tuning would be somewhat hard on a moving target. But orthos shouldn't take much time to settle down. So I'm looking forward to playing around and comparing these further.
They also need better pads, these are a bit too stiff and don't seal around the ear too well, causing bass to fall off a bit.