CPU and mobo upgrade after RX 460 upgrade

[ExuberantBlockhead]

bought my little bro (17 yrs old) a RX 460 for his birthday a few months ago, looking to upgrade his CPU and motherboard (if necessary) for Christmas

 

Honestly he is more interested in going to the gym (as a soldier, super proud of my little bro) and laying in bed, playing Tap Titans, than gaming. He does play League of Legends occasionally though.

 

So if you think I should get something more suited to his interests, than forcing a CPU upgrade on him, I am all ears.

(He does like wearing headphones as part of his outfit so maybe nice looking a pair of not Beats in the $100-$200 range? and maybe a DAC/Amp for his phone(S7 Edge))

 

little bro's rig:

A10-7850K

2x8GB DDR3

mATX motherboard

650 watt 80+ Gold semi modular

RX460 4GB

peripherals:

2x1080p

G710+

G502

G430

Bose Headphones

 

not planning to spend more than $300

motherboard must be no larger than mATX

planning to stick with DDR3, don't mind upgrading if within budget

 

also, does anyone know what a 14yrs old girl want for Christmas??