HiFiMAN EF-6 Headphone Amplifier (Playback 61)

Headphone amps and amp/DACs
HiFiMAN EF-6 Headphone Amplifier (Playback 61)
  • The EF-6 is a Class A, solid-state headphone amplifier that puts out a whopping 5 Wpc at very low distortion (<0.03% at 1W @ 1kHz).
  • Three switch selectable single-ended stereo inputs (two supported via stereo pairs of RCA jacks on the rear panel, one supported via a 3.5mm mini-jack on the front panel).
  • Two stereo headphone outputs (implemented, respectively, via a very high quality, locking ¼-inch phone jack and an also very high quality 4-pin XLR-type jack).
  • Two switch-selectable gain settings implemented via a rear panel mini-toggle switch. This feature addresses the fact that the HiFiMAN HE-6 planar magnetic headphone is roughly 10 dB less sensitive (or more) as compared to most competing headphones. In our experience, then, the high gain setting seemed to work best specifically for the HE-6 (or other similarly difficult to drive headphones), where the lower gain setting worked better for most other moderately easy-to-drive loads. As always, to minimize noise the best plan is to use the lowest gain setting that can produce adequate volume with the ‘phones at hand.
  • The EF-6 provides variable-level preamp outputs implemented via a stereo pair of RCA jacks.
  • Massive and robust build quality: the EF-6 is both larger and heavier than many stereo integrated amplifiers we have seen, in part because it sports an enormous internal power supply, with Class A MOSFET output devices that dissipate heat via huge, ribbed heat sinks stretching from the front to the back of both the left and right sides of the chassis. As you might expect, the unit runs quite warm to the touch, but never gets unpleasantly hot. The amp weighs approximately 24 pounds and exudes a rugged “overbuilt” feel.
  • The EF-6 volume control provides a precision stepped attenuator for optimal sound quality, accurate channel tracking, and low noise.
  • The amp features high-quality parts throughout.
  • Two-color status indicator light:
    • Off = amp is powered down.
      Purple = amp is powered up, but still in initial warm-up phase of operation.
      Blue = amp is powered up, warmed up, and ready to play.
  • Styling: The EF-6 features what might be called an “industrial chic” design motif, with most of the chassis metal work finished in a matte/crinkle-finish black. The EF-6 sports a thick, acrylic faceplate finished in gloss black with a recessed, matte finished center area surrounding the amplifier’s massive volume control knob.


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