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Reviewer: 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 1.89g in hybrid memory play with pre-allocated RAM and AIFF files up to 24/192; Audirvana 1.4.6 in Integer mode 1, Metrum Hex, AURALic Vega, SOtM dX-USB HD with Super-clock upgrade & mBPS-d2, RWA-modifed Astell & Kern AK100 with 2x64GB cards
Headphones: ALO-recabled Audez'e LCD-2, Sennheiser HD-800, beyerdynamic T1 & T5p, AKG K-702; stock-cabled HifiMan HE-6, HE-500, HE-300, Aëdle VK-1, Mad Dog/Fostex T50rp, Focal Spirit One, Ortofon eQ7
Headphone amps: Bakoon HPA-21 [on review] and AMP-11R, April Music Eximus DP-1, ALO Audio International
Headphone stands: Klutz Design CanCan, Sieveking Audio Omega, ALO Audio T
Powerline conditioning:   Vibex Three 11R
Review component retail: $4.900 with Solen polypropylene caps, $5.100 with Solen Teflon caps

The Studio Six from ALO Audio's Ken Ball of Portland/Oregon exceeds what most consumers need. That's because it will drive up to four headphones. Simultaneously. Without any losses in gain or sound quality. But who'd really need to? Without discrete volume controls even a headphone retailer or music seller who has folks listen before they buy might not exploit this feature all that often. With three switchable inputs, high gain and a stout power supply, the purely single-ended Studio Six accommodates the beastliest planars yet any volume changes affect the entire bank of quad-paralleled 6.3mm outputs in tandem. Having noted this unusual capability, most will thus treat the Studio Six as they would any other home headfi amp: for one listener, one headphone at a time.
But we do have to qualify 'as any other'. That's because the Studio Six aims high. Think $6.475 Mal Valve Head Amp 3, $3.995 Eddie Current Balancing Act, $3.500 Cavalli Liquid Glass and other high-priced valve-power assaults at the state of the union. Like its output socketry, the word valve here implied go forth and multiply. There are two 6V6 output bottles, one 5AR4 rectifier, one 6SN7 voltage-gain and two OB2 gas regulators. That's a total of six glow bottles. Studio Six. And built entirely in the US of A. Which wasn't as easy as writing it. "We've been delayed with the ST6 amp mainly due to improvements we implemented along the way as well as the fact that everything is made in the USA. Manufacturing here was more difficult than expected and took much longer when the goal really was a no-compromise headphone amp with a high standard for everything."


As the owner of 32Ohm Audio which operated out of a different downtown location before (it's since merged with the manufacturing premises as a by-appointment option) Ken is a shop'n'Internet retailer of headfi. He's constantly being solicited to cash'n'carry the latest and greatest. Whenever it's time to collaborate with chosen designers for his own brand ALO Audio, he knows going in what's going on and up in any given headfi category. He's no pale lab rat who never gets out to be blissfully ignorant of the market. He in fact does numerous international shows. And unlike most headfi makers his personal can arsenal is truly deep. Not just in theory does this account for the widest scope of impedance and sensitivity ratings. Finally his daily contact with the buying public is a constant reminder. What do actual punters want? What are they willing to pay? All of this educates ALO Audio products. You'd think that would be true for everyone's gear. It's not. Much high-end hifi is designed in an ivory tower.

That said here we are staring doggedly at a $5.000 6-bottle headphone amp that can drive four cans at the same time. Its mere existence suggests that Ken must have known how truly dedicated headfiers clamored for such a beast. That its particular feature set would seem overkill for mere mortals is no different than a garden-variety preamp with six inputs and four outputs. Most of us today use one source and one amp. Yet nobody faults a preamp for being excessively socketed. Perhaps invite the neighbors with the ST6? Of course five large are a very serious chunk of bread to butter particularly in the headphone camp. But it can and should equate to state of the art whereas with a speaker-drive integrated you'd still be in the mid level. Law of relativity and that.

The 6V6 beam-power tetrode was first made by RCA in late 1937. Some 76 years later it's still popular with guitar amps like the Fender Champ, Princeton Reverb, Gibson GA-40 and Mesa Boogie Lonestar to enjoy ongoing production in China, Slovakia and Russia. Because of relative similarities with the EL84 there are even adaptors to have a 6V6 socket take an EL84 (but not vice versa). The 6V6 is a lower-power variant of the 6L6 predecessor. It's good for roughly 5 watts single-ended, 14 in push/pull. With the Studio Six we knew from looking that it's a single-ended circuit or else there'd be at least four output bulbs. From popular lore we expect big tone because that's what the 6N7 and 6V6 are known for. But first some dirt from Ken Ball on the why, how and what of this machine...