I have a Beyer DT770 32ohm limited edition pair and now looking for a more energetic, forward sounding set to enjoy those moods and genres. My usage will be with my iPhone 5, but if an amp will significantly help, may consider (perhaps the FiiO E12?) It is the carrying of multiple gadgets and wires I want to avoid and thus the reluctance for amp. Almost all of my usage is out of home.
Am a little confused between the Ultrasone Pro 900 and Yamaha 500 Pro. I have tried both and on sound terms found the Ultrasones to be much better but am apprehensive if they can be driven well by my phone. During my audition I had to consistently keep my (phone player's) volume to around 90%. Yamaha 500 are very well driven but I found their sound piercing the ear at times, tiring and (perhaps) missed those nuances I got to hear so clearly from the Ultrasones. They are however much more portable and iPhone friendly.
Have also tried Beyer Custom Pro, Sony MDR 1R, Sennheiser Momentum but none sounded (to me) as good as the Ultrasones. Lately I have read some good reviews of Philips Fidelio L1 so I might try them as well.
Am a novice and thus this request for advice from you all here. Opinions/Comparisons of pairs mentioned will be highly appreciated (preferably in context of iPhone use without amp). If there is any other pair that you'd want to recommend, I'd be glad to explore.