Price Paid:  $4000.00 from online

Summary:
I'd like only to post my raccomandation to anyone wanting to carve out anything possible from his headphone sytem ; I've used the hp-4 clearly for the Grado ps-1 and hp-2 , but also for Sennheiser 6xx series and other brand headphones. The amp is utterly refined in producing the source' true sound character and add few coloration , not easy detectable really when in comparison with other hiend solid-state amps. There's sweetness in treatment of the signal but there's NO emphasys or lushness , or smearing on high or low end detail . it's completely free of grain and provide a fullload of power without crushing any part of the freq. spectrum . The softening is just as polite and kind of "microscopic" as to provide the right juice to interlink the different part of the frqs.

With Grado ps-1 and a refined source ( and good power ) is quite a dream, best overall dynamic headphone experience found until now ..

sound quality , construction , output , can be used as a preamp ( it's good as a preamp too ) detail and decay of notes on all .

Strengths:
ultimate headphone amplifier for grado heapdhones , hi end product, hard to sense coloration in sound , difficult to match all in all virtues as headphone amplifier .

Weaknesses:
Heavy , no balanced headphone out.
I have to say it ? not the last word on attach of notes ( bit soft on attach ).

Similar Products Used:
Many other headphone amplifiers .