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Ears-on time with Massdrop's affordable tube headphone amplifier

If you’re curious about tube amplifiers, the Massdrop x Eddie Current ZDT Jr headphone would be a great place to start.


The Massdrop x Eddie Current ZDT Jr headphone amp.


Eddie Current is known to the hippest cognoscenti for their high-end tube electronics, especially their headphone amplifiers. They're hand-made, artisan designs with prices starting at $2,450, so when I heard Massdrop had an Eddie Current amp in the wings I was eager to spend some ears-on time with this little guy, the $399.99 Eddie Current ZDT Jr Massdrop ships worldwide and the US price converts to £304 and AU$527.

The front panel has two 6.3mm headphone jacks, one specified for low impedance headphones (32-100 ohms) and one for high impedance (100-600 ohms) 'phones. The rear panel has stereo RCA inputs and stereo RCA pass through outputs (they cannot be used as preamp outputs). The amp's tube complement runs to two Russian 6ZH1P tubes and two 6N24P tubes. Before I forget to mention it, the entire amp is made in Russia. It's small enough to fit on a desktop, the amp is a tidy 6.3 x 4.3 x 8.7 inches (16 x 11 x 22 cm).

The sound of tubes

The Massdrop x Eddie Current ZDT Jr sounds like a tube amp, so it's rich, juicy, and most of all engaging. It keeps you coming back for more.

Once I plugged in a pair of Hifiman Edition X over-the-ear headphones I got lost in Ragnar Grippe's "Guilty" hard edged synth album. Rhythms popped, bass was deep and tight, this tube amp's low-end is flab free.

The Massdrop x Eddie Current ZDT Jr headphone amp's rear end.


Next up, my Grado RS1 headphones always benefit from being used with tube amps, and sure 'nuff the RS1 loved the Eddie Current ZDT Jr. The amp tamed some of the headphone's brightness while fleshing out the midrange a bit. Drummer Antonio Sanchez "Birdman" film score's dynamic punch was extremely satisfying, if you own a set of Grados and want to take them to the next level the Eddie Current ZDT Jr deserves consideration.

To evaluate the amp's capabilities with high impedance headphones I grabbed a set of 600 ohm Beyerdynamic T1s. This is another headphone that can sound overly bright, but here with the Eddie Current ZDT Jr the T1's sound with Sanchez's cymbals was vivid and clean. In fact, the T1's uber transparency took center stage, this tube amp wasn't softening the sound or thickening the tone of this remarkable headphone.

For comparison I brought out a $399 solid-state Schiit Jotunheim headphone amplifier and it was noticeably leaner sounding with Audio Technica ATH MSR7 headphones when I played cellist Yo-Yo Ma's recent and totally terrific "Bach Trios" album. I missed the tubes richer sound.

Which amp is more accurate? I'm pretty sure the Jotunheim is, but I'd rather listen to the Eddie Current ZDT Jr. That's a personal choice, you may prefer the Jotunheim's sound.

This Massdrop begins tomorrow, Friday, and is limited to just 375 amplifiers, and the drop ends on Nov. 29. So if you're interested in the Eddie Current ZDT Jr, don't hesitate.