I think it all comes down to our standards.
If the Matrix card is louder than 480, then there is no chance in hell I am putting that in my system, simple as that.
Maybe you are used to muffling noises with even louder sound from you speakers, but apparently not everyone is. I am more of a music lover and such loud sound would fatigue my ears real quick.
It doesn't get any fairer than head to head comparison like the one [H] did, btw. If you are so bugged about the sound, maybe you should buy/rent/borrow a 480 and do your own test and post it here

Neither of us have seen any of those card mentioned, so we are at the mercy of those reviewers. If you really must find the truth, be ready to pay the price.