I bought the E5 recently..Paired it with my Klispsch S4 and sennheiser PX 100,nd could barely notice any enhancement in sound qulity.As a matter of fact on the bass boost mode the soundonly gets muddier.Even though there is somewhat bass enhancement, there is o% improvement in sound detailing and clarity ! If this happened with a low end headphone/earphone I could blamei t on them,but on pairing it with anything of the class of S4 should have given a better response. So I thought of buying a better amp.The cheapes option , which is considerably talked bout the is Go Vibe derringer.Have a quote of 3350 for the same from moshel. Is there anyhting betteri n that price bracket,i.e. under 4k ?