Searching for the perfect amp for the AKG K-1000 - Part I

In July, I had called the AKG K-1000 possibly the world's best dynamic headphones. I had dipped Sir John's Imperial Seal deep into his royal-blue earwax container and bestowed a Blue Moon Award upon them. I also promised to be on the lookout for a suitable amplifier recommendation. You see, the K-1000s' retro-macho insensitivity of 74dB means they can't be driven by a standard headphone jack. AKG's stock cable terminates in four gold-plated pins to connect the 'phones to the speaker terminals of an integrated or power amplifier.

In July, I had also noted that the Ks suffered a peculiar propensity for emphasizing high frequencies that could overpower the remainder of the spectrum. This shrew was tamed only with my $6,000 Art Audio PX-25 SET to then produce truly world-class performance. Thinking the Ks to be less than copasetic with solid-state, my hunt for a price-matched amplifier concentrated on thermionic contenders, specifically integrated solutions that would keep such a headphone system simple and relatively affordable. A source signal could be derived from the tape-outs of an exisiting speaker system's preamp or integrated. Alternately, it could be Y'd directly from a source if the latter lacked a second pair of outputs. Simply adding one interconnect to this stew, you'd be good to go I reckoned, ready to style seriously in the privacy of your expanded skull.

Or so I thought until August when Stefan AudioArt's $179 headphone replacement cable arrived. Rather unceremoniously, it added itself to the cadre of must-invite, late-staying guests. It proved not only vital to get the most out of the AKGs (since then, I've purchased both the German cans and this proper "straw" to suck up all the musical calories they're meant to deliver), no, it suddenly also absolved the 'phones from any blame of undue HF emphasis or leanness. The onus for that goes to the blasted stock cable.

Properly chastened to trust my ears -- but not necessarily all hard'n'fast conclusions based on their evidence -- I could now revel in solid-state glory as parlayed by jacking the AKGs into the Bel Canto eVo2i. Of course, $3,200 worth of integrated amplification for a $529 pair of headphones was still rather far from realistic. It just proved a point - don't extrapolate reasons for why you hear what you hear. But, I had already contacted Tash Goka of Divergent Technologies whose Antique Sound Lab MGHead DT tube headphone amp has powered my resident Grado RS-1s for years.

At $750 and with 5/15wpc on triode/tetrode tap, Tash knew and admired the K-1000s himself and recommended the ASL MGSI 15DT that uses one KT-88 per channel. He promptly dispatched one to Taos. With apologies to Mr. Goka -- for diluting the original single-amplifier concept and letting my lustful eyes roam -- I then stumbled upon an announcement by Michael Barnes of Thai loudspeaker company nOrh. He was about to release a tube integrated with tube rectification and mirror-polished steel chassis for the unbelievably low price of $399. Having been mightily impressed with his overall value philosophy as well as two of his products (the ceramic nOrh Model 4.0 speakers and reviewed-in-these-pages synthetic marble SM6.9s), I knew his amp to have serious potential. I requested a sample. With all tubes installed, it arrived a few days later from Thailand.

On paper, both units had enough power to do the job and were priced perfectly to make a blessed financial match on the AGKs' prenuptial contract of dollars and dimes. But - would they also be a sonic match made in the higher heavens where the real pillowtalk happens? Today's report shall answer this question. But be reminded that if the Stefan AudioArt K-1000 cable were part of the equation, a good affordable solid-state or hybrid integrated -- say by Creek, Cambridge Audio or JoLida -- shouldn't be overlooked either.

With the Stefan AudioArt cable, the K 1000s' tonal balance is re-centered properly around the vocal range to banish any and all former veerings into minor stridency or undue sharpness. This now invites even hotter Pop recordings to join the party. Out of what field (left or right, solid-state or tube) you now pick your matching amplifier is no longer an issue of inherent headphone predisposition. It's purely up to your sonic predelictions.

The phones proper have already been covered in the original review. Before we start the sonic inquisition, let's take a brief look at the replacement cable and the two amps (both of which will receive their own feature reviews on regular speakers later).

nOrh SE-9 (left), Antique Sound Lab MGSI 15DT (right)
nOrh SE-9 (left), AKG K-1000 w. Stefan AudioArt cable (middle), Antique Sound Lab MGSI 15DT (right)
close-up nOrh back w. cable leads
Stefan AudioArt K-1000 cable
MGSI 15DT back with 3 inputs and 1 line output
MGSI 15DT from top showing tube layout
SE-9 from top showing tube layout
MGSI 15DT open
SE-9 open
stock K-1000 cable with pin terminations
The two amps are of equal width, with the nOrh just a bit deeper, the ASL higher (its input transformer is taller). Not owning a scale, both seem to weigh roughly the same.

Build quality is amazingly high considering cost. Antique Sound Lab pots only the input transformer while the full-width cover for the output transformers (clearly taller than the transformers themselves) rings when knuckle-rapped. nOrh pots all of its transformers and uses a mirror-polished steel chassis rather than black paint. Its connectors (RCA and speaker terminals) are nicer.

Both units use ceramic tube sockets; the MG's are mounted atop the chassis while the SE-9's attach to the floating circuit board. This gives the tubes a slightly submerged appearance. Half the bases of the rectifier and power tubes remain hidden.
Stefan AudioArt cable w. Cardas Rhodium spades

The MG's bias adjusts via trimpots and front-mounted meter. Being sited between the power tubes and longitudinal transformer casing, the pots require a long-stem jeweler's screwdriver to make adjustments without touching the hot tubes.

The SE-9 employs auto-bias and has no user adjustments. The MG sports 3 inputs and a line-out, the SE-9 accomodates two sources. The ASL uses a rotatry source selector, the nOrh a two-posiiton toggle. Both feature IEC power inlets to allow experimentation with after-market power cords. For more details, visit the firm's respective websites.

The AKG's stock cable (the detachable portion) is 10' long, the Stefan AudioArt cable half that. The captive wiring harness is 6'. Even with the shortened replacement cable, freedom of motion is still >10ft from the amplifier terminals.