I purchased the
TS-662 a while ago. I only used them once, the day I received them just to see if they work fine. I remember that there was nothing special about their sound signature so I just put them away and didn't use them again. Until yesterday night...
When I decided to check my headphone inventory to see if there is something there, that I can dispose of in one way or the other so I'll have less things to pack when I move to a new place. I took out a couple of headphones that I haven't used for a while and started listening, and among them were the TS-662. At first, they sounded hollow, with uncontrolled bass, not much detail and a sound stage that resembled a concert in a cave. When I was almost ready to take them off my head and throw them in a box never to be seen again, I covered them with the palms of my hands thinking that this may affect the sound. And guess what... It did. The echo of the cave was gone and the sound became 3D like where the band is positioned in a small and intimate circle with the listener in the middle. The bass became tighter and punchier, but not elevated and the micro detail became more evident.
I modded the TS-662 by partially sealing the cups, making it semi-open instead of the completely open.
These headphones share the same driver design as the PRO80 and the HI2050 though a bit smaller, 50mm instead of 53. TS-662 has a good driver that needed a different housing to really shine.
Sound signature wise, the TS-662 is a PRO80 with less bass quantity, more forward mids and bigger sound stage.
I think that those headphones have a great potential for DIY.