Headphone amps are usually pretty simple things. You get an input or two on the back, a headphone output on the front, and a volume knob. That's all you really need, particularly if you're not looking for one with a dedicated DAC (digital-to-analogue converter).

The Audio-Technica AT-HA5050H, which gets bonus points for sounding like an awesome website that we all know and love, is well beyond the curve. Far from being just ready for so-called "high-res" audio and expensive headphones, it's an amp that can satisfy those with headphone collections valued at more than a London flat deposit, provided you're willing to fork over a cool £3,500 (MSRP $6,000) to buy one. And that's only if you manage to find one in stock at all—the unit I looked at was apparently the only one in the UK at the time.

The AT-HA5050H is a headphone amp that assumes you have good knowledge of how headphones work, that you know about impedance, and that you know about the difference between a DSD audio file—that's Direct Stream Digital, the format used by Super Audio CDs that stores audio at a 2.8224MHz sampling rate—and a "normal" one.

The amp's headline feature is that it lets you quickly swap in headphones with different output impedances, from 120 ohms to 0.1 ohms. There are eight 6.3mm sockets on the front, split between 120Ω, 82Ω, 33Ω, and 0.1Ω outputs, and arranged in pairs for joint listening sessions.

Ohm y god

Getting the impedance correct is important for headphones. Those with a low impedance (generally less than 50 ohms) are typically used with portable music players or mobile phones that have weak audio output jacks, because a lower impedance means they have a higher sensitivity, and thus sound louder than an equivalent high impedance set when driven with the same amplifier.

However, in order to do that the coils of wire that make up the headphone driver are typically quite thick, and easier to manufacture. High impedance headphones use much thinner wire, lowering the mass of the driver, and reducing the amount of air between the windings, making the electromagnetic field of the voice driver stronger, and the sound less susceptible to distortion. The tradeoff is that high impedance headphones typically have a much lower sensitivity, and require more oomph to drive at acceptable volume levels, hence the need for a dedicated headphone amp.

A safe rule to follow is that the output impedance listed on the headphone amp should be less than one-eighth of the impedance of your headphones. The official blurb says the amp is intended for headphones with impedance of 16 to 600Ω. This makes the AT-HA5050H not just suitable for every non-electrostatic headphone currently in production that I've come across, but is able to tailor its output perfectly for different types. It makes the £1,300 Sennheiser HDVA600 look remedially simplistic, its single output impedance of 43Ω designed specifically for the Sennheiser HD 800. The AT-HA5050H goes much higher and lower than that.

Andrew Williams

Andrew Williams

Andrew Williams

Andrew Williams

Andrew Williams

The price is not just about cost, but design too. With a full size hi-fi separate frame and a frankly intimidating array of bits on the front, it looks more like a piece of lab equipment than something that belongs in a lounge. The volume meters on the front will probably excite any hi-fi nerds in the audience: they're Sifam units, one for each channel, and give the amp a clear retro air that feeds into its geek-embracing ideals. I'm a bit less convinced by the chintzy italic fonts Audio-Technica seems to plaster over just about everything it makes, though.

Getting back to the meat of the AT-HA5050H, it's a hybrid amp with a valve (tube) preamp section. It uses a pair of E88CC valves, which are there to provide the characteristic warmth that makes valve amps so popular. Audio-Technica says these valves are given 100 hours of burn-in, after which the best are put into this amp.

Sadly, they wouldn't tell me where the so-so ones end up.

The amp provides up to 2W of power, at 16Ω output. That might not sound sound like a lot compared to speaker amplifier figures, but it's huge for a headphone amplifier.

A modern sheep in retro clothing

While from a distance the Audio-Technica AT-HA5050H looks like it could have been made almost any time in the last 40 years, it’s actually a do-anything modern headphone amp—and the part that really makes it modern is the DAC section.

Around the back of the Audio-Technica AT-HA5050H is a S/PDIF input and a USB input, the latter letting you use the amp as an audio interface with a computer. There are analogue line and balanced inputs too, and in keeping with the whole "old but new" theme, you switch between them using a plain little knob on the front. Above this is a set of marked LEDs that tell you the exact sampling frequency and bit-depth of the current feed, and whether you're using a DSD format or not. The AT-HA5050H doesn’t half go for it, even if it is likely to make this amp seem hugely intimidating to anyone but a hardcore headphone enthusiast.

Should a £3,500 headphone amp be anything else, though? The rise of headphones has seen a huge upswing in portable amps and DACs, and often a lot of the price seems to be piped into fancy design and materials rather than functionality. After all, those that live for the audio and have money to spend on decent kit don't necessarily have the time to research what's really going on under the hood.

The Audio-Technica AT-HA5050H feels like an engineer's dream amp. It's a zero-compromise box that's wonderfully put together, and something almost nobody will ever need to buy. But if you do have £3,500 burning a hole in your pocket, well, you won't be disappointed.

Andrew Williams is a freelance technology journalist who has been writing in the field for 10 years. He covers just about all areas of consumer tech, with a particular interest in how it all works underneath the layers of glossy finish and impressive-sounding jargon. He can be found on Twitter at @wwwdotandrew.