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This is the fifth in a series of reviews dedicated to the concept of 32Ohm Audio as embodied by the store of that name in downtown Portland/Oregon and described here - Ed.

Srajan Ebaen
Financial Interests: click here
Source: Esoteric UX-1, Yamamoto YDA-01, iPod Classic 160GB, Wadia 170iTransport [on review], Meier Audio Corda StageDAC [on review]
Headphone amplifier: Yamamoto HA-02, Woo Audio Model 5 with EML 5U4G and EAT 300B, KingRex Headquarters, Trafomatic Audio Experience Head One [on review], Red Wine Audio Isabellina HPA w. Wadia battery power socket [on review], Burson Audio HA-160 [on review]
Headphones: audioTechnica ATH-W1000, AKG K-1000 with Stefan AudioArt wire harness to the voice coils, Sennheiser HD800 with ALO Audio custom cable, audio-technica W-5000, Grado PS1000
Headphone stands:: Sieveking Sound Omega
Cables: ASI LiveLine power cords and interconnects
Powerline conditioning: Walker Audio Velocitor S
Review Component Retail: $449 ($549 with 6-foot ALO Audio SXC cryo cable)

The economy is in the toilet, the audio hobby has a harder time justifying expenditures which could put food on the table, pay rent or attend to other basic necessities. Some of the hardier amongst the homo audiofoolicus species naturally consider listening to music a necessity only slightly less basic than a roof over their heads.

To those, the regulars at HeadFi would say, why not forget about a big system? Focus instead on really good headphones and a mini rig to accommodate them. With the iPod's rise to ubiquity, choices in headphones have exploded like spores. Naturally, many are more fashion item than serious hifi. Aiming higher—a lot higher—are AKG's K702. Since the firm's previous punishingly low-sensitivity K-1000 winged ear speakers, the K702 is their current rather more affordable and all'round less demanding circumaural and open-backed professional flagship. The 702 is essentially a K701 in black and comes with a detachable Neutrik-terminated cable.

Specifications include a claimed response from 10 to 39,800Hz and an input impedance of 62Ω. The detachable 3-meter 99.9% oxygen-free copper cord attaches left-handed via mini locking XLR plug. It terminates in a 6.3mm/¼" combo plug that converts to 3.5mm/1/8" for mobile duties. Wear weight is 235g/8.3oz, sensitivity 105dB/1mW.

AKG describes their flat-wire voice coil drive unit as running with a 2-layer Varimotion™ diaphragm which they patented*. The head band is dark blue leather and each K702 is individually tested and numbered.

As he does for a number of other headphones considered deserving but handicapped by their stock leashes, Ken Ball of ALO Audio** offers a custom cryo-treated cable dubbed SXC (silver times copper). I bought my pair with one and reviewed it accordingly.


** ALO is short for Audio Line Out


* The Varimotion™ descriptor is AKG speak for mechanical decoupling of the driver center to act as a quasi discrete tweeter without crossover. This dual-concentric behavior of a single diaphragm is something the English EJ Jordan drivers too have perfected. AKG achieves it by varying the diaphragm's thickness. Its "80µm center zone is virtually pistonic for well-balanced HF response while the 40µm perimeter is highly elastic to accommodate the increased excursion required for accurate midrange and LF reproduction." AKG's microphones embrace the same technology.

While still on the economy, dwindling discretionary hifi funds, frustration and desire, think iPod plugged into a Wadia or Onkyo type dock that can extract uncompressed files in digital form to pass on to an outboard DAC for superior analog conversion. This can become a bona fide source. If the necessary outboard DAC were built into the headphone amplifier... from a parts count and simplicity perspective, so much the better. If said DAC/headphone amp ran off long-lasting batteries which also fed the dock which fed the iPod... now we'd have the complete makings of a high-end and really smart headphone system.

Red Wine Audio's $2,500 Isabellina HPA with optional battery socket for the Wadia is one such beast. For a lot less, a USB-input mini headphone amp like the $150 Calyx Kong might be the ticket?