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Basics. Planarmagnetic or so-called orthodynamic headphones from Audeze, Fostex, HifiMan, MrSpeakers™ and Oppo tend to be nearly perfectly resistive loads. That means very linear impedance to eliminate or minimize undesirable response reactions to current mode's high output impedance.
With Audeze LCD-2 and Oppo PM-1 (under pillow during break-in)
What's more, as a breed orthos tend toward the lush, creamy and organic. They're generally not super lit up and airy like a Sennheiser HD800 by contrast. If you didn't mean to enhance these orthodynamic traits with a 300B amp like say my former Woo Audio Model 5 or an Eddie Current Balancing Act; or a lush non-DHT valve amp like ModWright's LS-100 or ALO Audio's mighty Studio Six - you'd want to manage them instead. Now a bit of accelerating grease-cutting blood-thinning action might be attractive. Enter the Bakoon current-mode outputs. They strip out what by comparison sound like overt colouration, fuzz and veiledness. This even goes for good transistor amps like Burson's Soloist and Conductor. Some could miss their cozy colourations to find current-mode bare-butt nekkid and somewhat pornographic.


Others could decide that all the alternatives are stuffily overdressed bores. Reactions are bound to be personal. What one reacts to simply tends to be quite unequivocal. Bakoon's sound—which obviously goes for speaker drive too—is best described as being lit up all over. Though it does mean a wickedly illuminated, informative and extended treble, this quality is not exclusive to the upper ranges. It's evenly distributed across the entire audible bandwidth. It makes for very high resolution at seemingly very close proximity. Think white light penetrating into every nook and cranny.
The Hindu deity Ganesha in Sadhu mode strategically covers the AMP 12R's bright white power LEDs.
By obvious implication, should you find a Sennheiser HD800 or HifiMan HE-6 with their stock leashes a bit hot and particularly the former a tad edgy, nervous and bright, the Bakoon treatment would only push them deeper into that undesired direction. Being a dynamic can with a cylindrical voice coil in a small gap to suffer inductive variations and impedance swings, such a load's response is also more likely to 'get cross' with current mode. The HPA-01 then gives you voltage mode to inspect where and how that might be the case. That said, even in voltage mode—softer of focus and transient handling—it's still a Bakoon to the core. It's an advanced modern take on 'see and hear everything' directly related to Crayon Audio's dedicated headphone amp. If you prefer moody half shadows and pleasant colourations, the HPA-01 in either mode won't be your cuppa. To wear my own colours proudly so you'll relate clearly to my biases, I find Bakoon and orthos magic. Their combo lands me more or less in the mythical middle of tone, flow, darkness and solid mass on one ear; and resolution, speed and upper harmonic finesse and energy on the other. Ortho transformation is particularly obvious with an innately chocolaty shadowed can like Dan Clark's MadDog and Audeze's more advanced LCD-2 v2 version of the same voicing. But to a lesser extent it holds true also for Oppo's PM-1, Audeze's LCD-XC and my various HifiMans on hand. I think of it as substance meets light.

With two Audeze on hand—my original LCD-2 v2 owner, an LCD-XC loaner—the AMP-12R beat the HPA-01's voltage output by a small margin. It sounded fuller and meatier. Like a more expensive amp with costlier parts and a beefier power supply. But particularly with the darker thicker LCD-2, the 01's current output had the edge over the costly two-boxer. With the XC current mode's advantage narrowed a bit. If I already owned that can and the 12R, I'd not be inclined to change. That difference wasn't sufficient enough.

With the creamily sinful v2 meanwhile I felt that the 'counter action' of the HPA-01's current drive made for the most ideal match in my hardware inventory. Yet to me Sennheiser's HD800 sounded better in voltage mode. Hence for it my nod went to the big 12R. Obviously that amp isn't the focus of today's assignment. So we'll remove it now from any further considerations. Blip. Comparing the HD800 on the HPA-01's own two outputs, I found especially the bass inferior in current mode. Texturally it grew too bloomy as though control was inferior. On the other end of the audible range I found that current mode emphasized the very treble brightness which has always bothered me a bit with this German statement headphone even with my aftermarket ALO harness.