Audio Technica AT-HA20 Headphone Amplifier Review

Aloha!

I avoid doing reviews on stuff that I cannot find any research material for, but I am going to make an exception for a neat headphone amplifier that I picked up in a secondhand store in Japan. Today we are looking at an Audio Technica AT-HA20, which I believe was never sold in the States.

I did not have a chance to try out this unit in the store, and have to admit I was initially puzzled by its appearance. Why stick a clear top on this thing if there is so much empty space inside, with nothing much to see? Then I plugged it in and had a moment of clarity. It turns out that the factory put a bad-ass blue LED inside so it lights up the cavernous interior and entertains the user. ‘Nuff said.

This amplifier has a clean appearance, with a machined aluminum case and the aforementioned clear top. The user interfaces on the front are kept to a minimum, with a power switch, ¼-inch and 1/8-inch outputs, and a volume control. On the back are stereo RCA inputs and outputs. The whole thing is powered by a hefty AC adaptor, and there is no battery option for this baby. It is really easy to set-up -- just find a 1/8-inch to RCA adaptor and you are good to go.

Beside not having a battery compartment, the size of the AT-HA20 keeps this from being a portable unit. It measures in around 1 ¾ x 4 1/8 x 6 inches, and it weighs a little under a pound. This is a good size for the desk, as it does not take up too much real estate, and Audio Technica put rubber feet on the side too so you can stand it on end if you want to.

The amp requires 500mA of power at 12 V, so it is not a real power hog. It has a maximum rated power stereo output of 100mW per channel at 32Ω with a total harmonic distortion of 0.5%. During normal usage at a more reasonably 20mW output, the THD drops down to less than 0.08%. The rated frequency response is 10 to 100,000Hz.

One of the reasons I use a headphone amplifier is to increase the volume when using high-impedance headphones with my laptop or iPod. The AT-HA20 does an admirable job of this, and the 64-ohm Sennheiser HD280 Pro cans that I use at work have plenty of output when running them with this amplifier.

The other reason I prefer to use a headphone amp is to improve the overall tone that I hear, and this is a lot harder to quantify and describe. But, with the added headroom, a lot more detail becomes evident, and to some degree the circuits will alter the overall sound of the source music. I find that theAT-HA20 is amazingly neutral and does not add much color to the sound, with a mild boost in mids and perhaps a slight increase in sibilance.

So, this amplifier also spruces up the sound of headphones that are maybe not too great, like my cheap-o Sennheiser HD 201s. It enhances the weaker registers, and gives the phones a more balanced overall tone. Overall, this was one of my better secondhand store finds, and it has taken up permanent residence on my desk.

After doing a search online, I am pretty sure that the Audio Technica AT-HA20 has been discontinued, but there is still some old stock out there, and a guy in Hong Kong is selling them $116 on eBay (with free shipping). If you have been jonesing for a headphone amp, this might be a good place to start.

Mahalo!