Top Performer at a Budget Price.

I was enjoying these just fine using an RSA SR-71A portable amp. Quite powerful little amp for a portable.
Recently purchased a Channel Island Headphone Amp with upgraded Power Supply. Wow ! I thought I had heard the HD650 but in fact what I had been listening to was trash compared to what these are capable of when properly amped. Expansive soundstage, deep, powerful bass, crystal clear highs and a midrange to make you drool. Top notch headphone ONLY if you feed it properly.