I've been thinking of upgrading the source of my music for a while since I got my SM3's. I currently play music off an iphone 4s and was thinking about getting a portable headphone amp but then thought I may as well get something that is all in one. I've had a look around some of the products and my problem is that they hold a too small amount of music. I would need at the very least 64Gb of space and that is for mostly 320kb music and I will be trying to upgrade the majority of my music to flac. The other thing is that a lot of the DAP's i've been looking at dont seem to be of a very high build quality.
I'm willing to spend a bit of money, maybe up to $500. Can anyone point me in the right direction?