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As headphone amp.
Having owned Grado RS-1s, Sennheiser HD 650s and currently holding on to completely rewired AKG K1000s and Beyerdynamics HD800s, my favorite headphones of the bunch are the audio-technica ATH W1000s. Personal bias and preferences demand just the right headphone amp for those. My magic weapon has been the Yamamoto HA-02 whose Shashi Cherry deck also matches the W1000s' ear cups to perfection. No coincidence there if you know the connection. Equally compelling though distinctive is Trafomatic Audio's Experience Head One in for review. The Yamamoto has two inputs and speaker outputs (though what the latter can realistically drive considering the low power output is open to debate). The Trafomatic has preamp and subwoofer outputs; three different headphone impedance tabs carried on discrete output transformer secondaries; and two inputs switchable by rear toggle.

Both Japanese and Serbian can amps are tube powered. The latter is even tube rectified. It's this context the Isabella slipped into upon entering my headphone lounge. This extension of my office really belongs to Blondie the Cyprus cat. Clint Eastwood's character in The Good, The Bad and The Ugly was the man with no name. This cat doesn't know her name from Adam so you can call her anything you want. Blondie seemed appropriate then. Okay baby, make room for daddy now.

I had some assumptions hunkering down in Ikea's trademark lounge chair which I have surrounded by Ikea bathroom racks 'n' shelves cross-purposed for audio (that four-tier wood stand is simply perfect in width for the RWA gear and opened MacBook). Isabella as headphone amp would be quiet. It'd have plenty of gain. And it'd be overshadowed by the tone density and expansive color palette of the other contenders. It was, it was and it was. Before we continue, let's grab the wallet. The particular appeal of the fully gussied-up Isabella with DAC and headphone module is that the latter two hitch a free ride on batteries and chassis. You're not paying for two spare enclosures, four extra batteries and two chargers. That's where the $500 headphone option makes sense (the two other stand-alone machines are about twice that and don't include a digital converter). And though Vinnie's headphone module is transistorized, pulling out the 6922s cuts the sound. The valves are squarely in the signal path.

With the Beyer HD880s, the Yamamoto had the most intense vocal band, the Trafomatic the strongest bass. In terms of color 'pop', the Isabella was palest of the three. That's also a reflection on the headphones. They strike me as very correct in hifi terms but rather less endowed than the audio-technicas when it comes to inducing a compelling emotional response. I use the 880s for reviewing, the W1000s for listening. Turning this argument around, the HA-02 was the most additive (addictive?). It made the 880 stew the most fanciful and flavored of the bunch. That's not the same as calling the HA-02 the most honest or linear. In this context -- in my case with a big grin -- you could certainly accuse Shigeki-San of energetic enhancements in the midrange.

The far higher sensitivity of the Japanese cans kowtows to my hi-eff speaker leanings. Perhaps that explains why I consider them in a different league from the Beyers. They simply put you deeper inside the musical action. Here they allowed me to take close note of the Isabella's drier textures. Those performed the kind of damping effect I also hear from huge transformer-coupled power conditioners. Something about the innate tension, wiriness and tickle factor of the musical energy is stepped down. It is tamed and more relaxed.
That last word is in fact a core attribute of the Isabella's voicing or gestalt. We will encounter it again on the last page which deals with its performance as a preamplifier. The Isabella is about relaxation and an organic as opposed to high-strung showy feeling. It's not about deep voluptuousness. Nor is it about extreme micro dynamics. Back to the headphone socket. Coincident with the minor damping -- you could also view it as a direct side effect -- is very concise articulation across the entire
bandwidth. As a loudspeaker, we'd immediately detect a sealed, not vented box. This is particularly true in the bass which lacks all flab or looseness. But unlike the Zu Audio Presence and Definition speaker models which marry sealed alignments with high voltage sensitivities for a rocking feistiness whose articulation goes hand in hand with punchy dynamics, the Isabella headphone output is more toned down like my DeVore Fidelity Nines.


Considering the $500 option sticker, I flash on Ray Samuels' even cheaper op-amp designs. They might be the stiffest competition and preferable if you're just shopping for a portable device to jack your headphones into. The Isabella package then won't have your name on it. If you're a speaker listener however who wants to add quality headphone functionality without upping the box or cable count in the stereo rig, Isabella's 3-in-one offering is very attractive if you don't mind the backside location of the headphone input.


To wrap up headphone comments, resolving power and control are very high and the general presentation is laid-back to remain non-fatiguing over extended sessions. Neither pipe 'n' slippers nor adrenaline brigade, I'd characterize this performance focus as relaxed resolution. Subjective lateral soundstaging beyond ear width is very good, wraparound depth good. Curtain call (when all the audible elements arrive to become equally important) occurs at somewhat higher levels to where this headphone socket wouldn't be my very first choice for low-level listening. If you're a high-power can fan though who loves to crank it, long-term comfort is exceptional precisely because energy distribution is very even and squarely non-forward. If the headphone geeks at HeadRoom are correct about Denon's new AH-D7000s dishing out an extra octave of bass over all others they've encountered (these guys have listened to practically everything on the market), the Isabella's hi-current grunt in the low frequencies could be the perfect weapon for those "Mariana Trench" dives into infrasonic depths?