For maybe 250 dollars you can get Elemental Watson, which I like a lot because of its cost-performance ratio with its price range (below 300 dollars). Probably the CP king given everything I have tried and compared below 300 dollars. It's a duo mono design amp, which really helps channel isolation (reduce channel interference). The result is a much cleaner sound, instrument isolation, and larger soundstage than those without duo mono. Then Watson also have the class A design, which helps the sound delivers a faster speed and cleaner sound. http://www.head-fi.org/t/823002/elemental-watson-class-a-valve-mosfet-hybrid-headphone-amplifier-review-added I have paired Elemental Watson with my previous HE400i, and it sounds quite impressive for its price --- though it did took around 100 hours to burn in.