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This is the 42nd 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.
Reviewers: Srajan Ebaen
Financial Interests: click here
Source: 27" iMac with 3.4GHz quad-core Intel Core i7, 16GB 1.333MHz RAM, 2TB hard disc, 256GB SSD drive, ADM Radeon HD 6970M with 2GB of GDDR5 memory, PureMusic 1.82 in hybrid memory play with pre-allocated RAM and AIFF files up to 24/192, Antelope Audio Zodiac Gold/Voltikus, Esoteric UX1/APL Hifi NWO-M with 24/192 async USB input, Cypher Labs Algorhythm Solo, Metrum Acoustics Mini NOS DAC Octave [on loan], April Music U3 [on loan], April Music Eximus DP-1
Preamp/Integrated: ModWright LS-100, Schiit Lyr
Portable amps: ALO AUdio RxMkII
Headphones: ALO Audio recabled Audez'e LCD-2, Sennheiser HD800, Beyerdynamic T1, AKG K702; Ortofon eQ7; HifiMan HE5LE, HE500, HE6 [on loan]
Cables: Complete loom of Zu Audio Event, Entreq USB and Firewire cables
Stands: 2 x ASI HeartSong 3-tier, 2 x ASI HeartSong amp stan, Klutz Design Cancan, ALO Audio T, Sieveking Sound Omega
Powerline conditioning: 1 x GigaWatt PF2
Review component retail: $485 for the Continental ($620 with custom-fit cable); $349 for the Slim; $1.595 for the modified T5p
"Opening up our little tube amp is a bit tricky. We use some soft epoxy to keep microphonics way down
and prevent the battery and board from moving anywhere."
Ken Ball's ALO Audio Continental portable tube hybrid headphone amp nearly didn't see the light of day. Actually that's not true. It had already been birthed into production when it occurred (this not being melted guts from tubular heat but an unauthorized clone of the Continental advertised on Ken's own supplier's website under a different name). Some Chinese OEMs just don't get it. Thankfully this one did. After the fact. When Ken announced that he'd ditch a good year's worth of development work and walk away from the project after honoring his buy-in commitment of the first run, the OEM pulled the unauthorized clone with a firm promise to honor the exclusive. Of course our dufus had already silk-screened 100-some enclosures with the wrong name just because. Ever the gentleman, Ken offered to carry half the rebranding costs. In an effort to meet unrealistic consumer expectations for high-value goods, Western manufacturers routinely face all manner of heart aches. On this count of yellow fever, Ken was this close to pulling the plug - the upshot being never again. Good for us that he didn't even though never again will likely stay put. Heck, this isn't about cultural differences. This is about theft of intellectual property and basic lack of respect.

Not that the Continental would ever become any large-volume enterprise. Perhaps that's why the OEM got preemptively creative. This amp is clearly promoted as a Limited Edition. With a $485/$620 retail* for an iPod-sized but far fatter pocket rocket (120 x 72 x 27mm), we're on rarefied turf for the breed. More to the point, the sub-miniature Raytheon 6111 tube—we've previously seen it or a cousin thereof in Audio Aéro digital, Audio Note UK and Music Fidelity machines—is of limited new-old stock availability. Whilst its rugged ultra long-life military origins promise 100.000 hours of use with long flexible leads hardwired to the board, Ken naturally keeps replacements in stock. There's only so many continental breakfasts he can serve with proper seconds and thirds. For caps he uses Sanyo PX military grade with an expected life span of 192.000 hours when used at 65°C. The tube heaters run a regulated 6.3V, the plate sees 90V off a steup converter and the discrete FET output stage runs on +/-12V. Power output in ohm/mw is 16/740, 32/500, 50/440, 300/250 and 600/125.
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* The raw amp is $485. With custom-fit cable (iPod to amp) it is $620.

With a 6 to 7-hour run time from a 4-cell 16.8Wh 12V/1400mAh Lithium-Polymer battery (3 to 4-hr. recharge) for its stated 2.5-watt power consumption, the Continental's output FET and overall tube voltage gain are advertised as ideal for stationary fullsizers à la Sennheiser HD800, Beyerdynamic T1, AKG 701/702, Audez'e LCD-2 and other 32-ohmers. Claimed S/N ratio exceeds 100dB and input impedance is a high 30KΩ. While I own all of these headphone beauties plus audio-technica's W5000 and have on long-term loan three HifiMans (5, 500, 6) from Fang Bian, sense and sensibility for portable headfi demanded I use something a bit different on my noggin.

Why different 'phones?
Enlarge!