Most pure analogue headphone amplifiers are simple affairs with a volume knob, some gain adjustments, and that’s it. And then there is the Manley Absolute Headphone Amplifier, which has so many controls and adjustments that even an experienced reviewer will probably need to glance at the owner’s manual at least once. Instead of a simple circuit path, the Manley delivers two, and instead of a single global feedback setting the Absolute offers a 10 dB range of adjustment. Intrigued? I know I was, and I continue to be amazed by the flexibility and sonic adjustability of the Manley Absolute Headphone Amplifier. Let’s take a look and see what absolute means when it comes to a headphone amplifier.
First off, in case you didn’t glean this from the photograph, the Manley is a valve-based device. Its valve complement includes two 12AX7 input valves and four 6AQ5A (EL 90) output valves. Its rear panel has two stereo pairs of single-ended RCA inputs. For outputs the Absolute supplies one single-ended RCA stereo pair, one 6.35mm stereo headphone jack, and one balanced 4-pin XLR headphone jack, which allows two different headphones and one line output to remain connected at all times. The rear panel also contains the AC mains connection, the Headphone Maximum Level adjustment threshold control, and an instruction panel that lists the controls and their functions.
All the controls are on the front of the unit. These include a large volume control thumbwheel with LED level indicators directly above it. Directly to the left side of the volume control is the push-pull/single-ended selector, which changes the amplifier’s circuit topology. On the right side of the volume control is the mute button. On the top surface of the Absolute you will find two rows of controls, the lower row contains, from left to right, a three-way output impedance adjustment, output selector, input selector, mono/stereo switch, and an EQ on/off switch. The second row has a variable feedback adjustment knob, bass control, treble control, and balance control knobs. The Absolute comes with a dedicated RF remote control that has only two buttons: volume up and volume down.
Installing the Absolute was easy: simply connect a source to the input and a pair of headphones to the output; turn it on; select the correct input, output, and impedance from the front panel controls; and you’re done. I used a wide variety of headphones with the Absolute, but the Abyss Diana Phi and Focal Elegia spent the most time connected to the Absolute.