That depends on just how picky he is in terms of sound quality. I use my USB DAC/Amp with a pair of Grado SR-125i headphones for listening to music. For reference the DAC/Amp I'm using is an Alpha Design Labs Stride
which would completely shoot over your budget and it's just for playback, not for recording. For now I think we're best off focusing on the components of the PC itself:
CPU: Intel i3 3220
Motherboard: ASRock B75M-DGS
RAM: Corsair 2x4GB DDR3-1600
So that brings your total to right about $230. I'm not sure which Creative card you have (not a big fan personally) but he may want to consider looking at an Asus Xonar DS or higher if he's willing to spend the cash.