And don't be a pussy. This is not some personal nonsense. I can relate to his 11 year old, whether or not anyone is audio person or not. And there is no way to tell if one thing sounds better than another, without listening to many. Sound is subjective to each individual.
1. I'm sure you can relate to his 11 year old...
2. For the most part, music is not subjective. People can listen to music, but to truly
LISTEN you need to sit down with someone who actually knows music and can explain it. If you don't understand that, then you don't understand music. If you're buying a $300 set of headphones, then you damn well better go to some audio store (or even your local music-teaching location) and listen to some real music.
How do you know if a snare drum sounds like shit on your headphones if you have no idea what a snare drum is supposed to sound like?
It's like eating transfat loaded sodium laden Mcdonalds and saying "It tastes good!" because you have no real basis for comparison.
However, to go back to the OP's post, NO 11 year old needs $300 dollar headphones. Take the kid to an audio store, have him close his eyes, and then have him listen to 8-10 different sets that are under $50 as a double-blind test. Throw in the beats somewhere. If he chooses the beats, well then you've got a kid who actually knows what he wants. If not, you've got a sheep. Lead him in the right direction.
(He still doesn't need $300 headphones).