I just finished performing the Lawton acoustic chamber dampening modifications on my TH600 and it's the best 50 dollars I ever spent. Like lots of guys, I upgraded from D2000 headphones to TH600 because of the D2000 missing midrange. However, the TH600s seemed to replace the authoritative sub-bass of the D2000s with a rather annoying mid-bass bump. Also, the TH600s had a harsh upper midrange bump that dominated the treble. I considered selling them but used TH600s are hard to get rid of, unless of course you want to practically give them away. Mark Lawton to the rescue. To avoid throwing good money after bad, I purchased his Level 1 mod kit and installed it myself. He was a good chap to work with, and I'm convinced he knows his stuff. However he estimated 1-2 weeks for shipping and it was 4 weeks. Also, the kit was missing a few pieces which he kindly provided after an additional delay. So after a few weeks, I was finally ready to perform the Lawton acoustic chamber dampening modification to my TH600s. The kit is designed to dampen the TH600s in 3 locations: earcups, and 2 concentric metal rings on the backplane. The inner ring correlates with magnet size and the outer ring correlates with diaphragm size. I applied the standard "tap" test to these locations and they all rang like a bell, so Mark selected the correct locations to dampen. Hard to believe headphones this expensive could ring so much. After the kit was installed, I retested and determined the ringing had been highly attenuated. The kit includes numerous precut rubber pieces with glue already applied to one side. If you are familiar with Dynamat, the Lawton rubber is much harder and thinner. Three olive rubber pieces are provided for each earcup (6 total), and 2 black rubber pieces are provided for each concentric ring (8 total). There is an extra black rubber piece I didn't use. Finally, a gray foam piece, with 2-sided tape already applied, is provided for each earcup (2 total). I suggest you ensure all the pieces are present before beginning your TH600 modification. I installed the kit according to the instructions Mark provided me, but he left out a few details. First, most of the rubber pieces are only approximate size, so they must be pre-fitted and trimmed to fit. However the round pieces on the concentric rings already fit perfectly. Second, for any rubber piece that does not fit flat, the provided glue is not aggressive enough to hold it in place. I added a very thin layer of superglue to the black rubber strips, and I used ample amounts of 3M 2216 epoxy adhesive on the olive rubber pieces in the earcups. An application note for the 2216 epoxy: This adhesive is excellent but expensive, I had some left over from a previous project. A cheaper substitute would be a thick superglue such as Loctite 1752196. Thick adhesive is necessary because the olive rubber pieces are distorted so severely during installation, there are gaps that must be filled in order to maintain proper contact with the earcups. The 2216 epoxy requires the parts to be clamped overnight, I can provide the clamping procedure if anyone is interested. I tested the TH600s with the dampening kit and OEM earpads installed, using my Burson Soloist. The difference was quite apparent between undampened TH600s. The mid-bass bump has shifted downward to provide a smooth, powerful low end. The harshness in the upper midrange is vastly reduced, revealing a crisp high-end I didn't notice before. With the extreme frequencies out of the way, I can detect a new separation and clarity of midrange frequencies. Presence is comparable to my LCD3s but with more body. So the verdict is: The Lawton TH600 dampening modification provides the tonal balance I wanted to begin with. In my opinion it makes the TH600s world-class headphones. So if you own an unmodified pair of TH600s, you owe it to yourself to install the Lawton dampening modification. It's easy and cheap. I haven't installed the angle pads yet, I will update later if they make a big improvement. Doubt they will help as much as the dampening modification though.