My #1 recommendation is the CAL!:
I don't know anything about the gaming headphone.
So the CAL is good, right ? Is CAL better than AKG K450 in comfort and sound quality ? Is it better than Sen HD202, K240 Studio ?
And, if i dont find the CAL, is AD500 a good choice ?
What I can tell you is the the CAL! is the best choice for the needs you described--base on U.S. pricing.
The K 240 is also good, but your computer on board audio may not be able to power it well enough to satisfy you.
I have not heard the downline AD 500--only the AD700 & 900.