Hey guys, I thought I would jump on this thread since I came across it. I've been using a Tiamat 7.1 for two years now, and I feel like I can contribute something to this discussion.
When I first got the headset, I was upgrading from a Logitech G930, and the first thing I noticed was that the Tiamat wasn't as comfortable around the ears. The G930 will squeeze your head like a watermelon until you break in the aircraft grade aluminum, but the Tiamat was much more forgiving. To be clear, you will never snap the plastic on this headset unless you grab each ear cup, and try to rip them apart like the Hulk. It isn't poorly designed, and it doesn't feel cheap. The ear cups are a little smaller though, which is a negative for me.
The sound quality, which is one of the biggest points, is great. For the first year, I simply used my built in 7.1 on my MoBo. It was better then the virtual 7.1 on the Logitech G930, but it was only a minor improvement. The real "advantage" to it was in games. I play a lot of first person shooters, and I rely heavily on audio. In games that provide adequate audio support (such as Battlefield 4), I'm able to hear a footstep behind me, and knew 'precisely' what direction it came from as well as how far away. Definitely a plus. However, for music, this was no better then the Virtual 7.1 of the G930.
The second year that I've had this headset, I bought myself a sound card. I didn't expect a huge different, but wow. I was blown away. When you combine this with a sound card, it blows any virtual 7.1 headset out of the water. The bass was and is the most incredibly precise bass I've ever heard outside of real life. I've heard giant speaker setups with subwoofers the size of a small car, and they are louder, but you can't compare the quality of the sound. It's clear. If you end up with a 7.1 headset and a sound card, I recommend watching a Transformers movie. Especially the last one. And the rest of the audio was incredible as well for music, which was another plus.
The biggest flaw is the mic, which looks like it was tacked on as an after thought. You're better off buying a cheap desktop mic or a clip-on one if you game online with friends, or talk regularly over Skype. The quality is okay, from what my friends have said, but it feels very cheap, and crapped out after a year. The good news, is that it can be slid back into the headset. I suppose it was meant to be a design feature initially, but when it breaks, you can slide it back inside, and pretend the headset doesn't have a mic anymore.
The reason I came across this thread is because I was looking for comparisons between this headset and the Strix 7.1. The Strix is the first real alternative to the Tiamat if you're looking for True 7.1 in a headset, and it looks good. It appears that it has larger ear cups, which is a big deal to me, and the mic should be better (can't really be worse). I can't really imagine the audio being better, but I'm sure it will be excellent. All in all, when this headset finally breaks in a few years, I'm going to try out the Strix. If you're the type who doesn't want to take risks though, avoid all the reviews, and try out a Tiamat. You won't be disappointed.