The HP4 uses 6SL7 valves, properly matched to the load through de Paravicini’s renowned transformers, to deliver nearly 1W of high quality, low distortion power into high or low impedance headphones. The output circuit configuration uses de Paravicini’s ‘Enhanced Triode Mode’, as employed in the highly successful V20 and 859 integrated amplifiers, while the input is also transformer coupled, giving the flexibility to accept balanced or unbalanced signals from the preamplifier.

For the greatest user convenience the HP4 has its own volume control, while input signals can be independently switched through to the power amplifier for headphone and/or loudspeaker listening. As with all EAR products, reliability is paramount and valve life is in excess of 10,000 hours.

Positive Feedback Review
After 10 years in virtual obscurity, the E.A.R. HP 4 Headphone Amp is now a big-time phenomenon. With conventional headphones approaching the $2000 price point, this high-end E.A.R. masterpiece makes real sense. A sonic leap over the most extravagant competition known to me or my audiophile friends and associates, the E.A.R. is the best of the best for maxing your cans with any source. The HP 4 is a recording engineer's must own. It is the first headphone amp to embarrass and out-perform electrostatic phones, with top notch conventional cans sounding better. The HP 4 cannot be ignored or surpassed. To hear the E.A.R. HP 4 is to own it. I bought the review sample. It is the state of the art!