Keep in mind I demo the FW10K at noisy environments. The vents are large. Bass levels will naturally plummet. Whereas CL2 and Z1R provides better isolation so they don't lose as much bass in those equally noisy environments. I've said that the FW10K would probably sound better at home or indoors, but at that point I rather use headphones since IEMs are on the go for my usage. Perhaps the new Spiral Dot tips would help it create a greater isolation, but the vent will always still be there so the amount of isolation one can get is very much limited.