So I'm currently rocking a Rocoo-P and the Sennheiser HD 428, but I'm definitely planning to upgrade. I'm probably going to buy the Ultrasone Pro 750, and I'm wondering if I should upgrade my DAP? Or should I just purchase an external amp like the fiio E11 or E12? Or even nothing at all? I do listen to more bass heavy stuff, but I prefer the lows to be quick and punchy, not slow and drawn out. Plus half of my library is filled with classic rock and other more, higher end spectrum tracks. All FLAC, for obvious reasons. I just really would like to know if it is worth upgrading my DAP, or if the Rocoo-P would suffice. My budget for the DAP is bellow $150, and an amp (if recommended) would be bellow $150 also. P.S. If anyone wants to throw their opinion out there, I'm looking at the Ultrasone Pro 750, Denon AHD2000, or the Shure SRH940. Any opinions are greatly appreciated. I just want to upgrade.