I love my Pro 900s (only at about 20 hours now)! I've been thinking about getting an amp after they've had 300-400 hrs. I currently have a Fiio E7 I run directly out of my MacBook Pro. Is there a better option (full-size or portable) for the Pro 900? Not really on a budjet (I'll sell some equipment if I must) but the cheaper the better. Not sure if important but I listen to everything minus country. Looking for a good bass response from the Pro 900 as well as all other quality upgrades an amp can provide for the Pro 900. Thanks!