Quote: The Isurus is more in line with a higher end sound. They have a wider stage, the clarity and detail is exceptional on the Isurus. It is a brighter more analytical sound signature. The SHE3580 is a very smooth listen but you want sparkle AT is known to have that. As for bass dynamics. Both earphones are great in this department I didn't find either of them to have anything muddy at all. The bass on the isurus is a bit more tighter and complete over the She3580. But the SHE3580 is very satisfactory even for guys that like bass heavy iems. I have grown to hate muddiness in bass. That SHE9550 or even the MEElectronics CC51 which is supposed to be clear.. Not the bass.. Quote: You are right in that it could be the CKM77 as well. It is using one of the 2 as the Isurus is right in the middle but since these use Aluminum housing just like the Isurus these might be more closer to the sound of the Isurus. I think all these have similar sound signatures and marginal improvement in sounds over material and sound tweeks but once you guys get your Isurus read the many reviews on the CKM99.. Especially Jokers..You never know the Isurus could be a hybrid of the 2 that AT developed just for Thermaltake. Who knows. The only real way to know if someone cracked open the housing and took a look at the drivers themselves. I do know that they are AT drivers I am certain of it.