I owned the HD800s and have a lot of respect for them, but sold them due to preferring my R10s and O2s at the time. I'd been very curious about the T1, and although a meet setting is less than ideal, I was able to listen to them on numerous rigs at CanJam, and was able to spend about an hour after hours with them on Pete Millet's Pinnacle and Apex amps and Todd's Meridian source along with the HD800. Although I think the T1s are very good closed headphones, the HD800s continued to impress (still not enough to want to own them), and the T1s disappoint. The Monkey and I were basically just sharing and enjoying music (had my CDs), and neither of us really wanted to use the T1s, so switched back and forth to share the 800s. When it was just about the music, we both wanted to hear it with the 800s.