Vive la différence. First evidence that Rev D had indeed revised and rev'd up sonics came from an unusual experiment. Enter Raal Requisite's groundbreaking SR1a. It's the world's first true-ribbon headphone. It sits at the tail end of more than 10 years of R&D by the ribbon tweeter experts at Raal. With a near-short load impedance due to no matching transformer—that would add 2 pounds of wear weight—there's instead an amplifier interface. This passive black box plus included headphone cable create a steady 6Ω load impedance. They also build in a de-emphasis circuit which offsets the rising response of this small line source. To feed the ribbon with maximally 5A of current but only about ½ watt, our plain black box attaches to a standard ~100/200wpc into 8/4Ω speaker amp via provided banana links. This deliberately burns off 95% of your amp's power resistively. Otherwise 150 watts into ribbon 'tweeters' would be silly. But it also provides the requisite current for challenging bass transients at high amplitude. Due to this interface, an amplifier's damping no longer factors as it would with loudspeakers.The interface now works as a current source.

Soundaware A280 SD card transport ⇒ COS Engineering D1 DAC/pre ⇒ Nord monos ⇒ impedance adapter interface box ⇒ SR1a

As an AKG K1000-style floating open baffle with adjustable wings, our Serbian invention has no ear cup, period. Unlike a planarmagnetic, it also has no in-the-way magnetics. It suffers no ear-muff syndrome of trapped air, sweaty ears, turbulence and structural reflections.

Add demonstrably superior impulse response and unleashed dynamics all within a centimeter or two off your pink bits. In your mind's eye, see speed, dynamics and resolution at most unfamiliar potency. As you'd expect with a ribbon, HF extension is fabulous. As you'd not expect, bass is good to about 30Hz. As common sense will tell you, bass stripped from resonance and without being loaded thus pressurized by ear cups will be most precise and quick but also leaner than the norm. Think of ear cups as miniature rooms hanging off your skull doing all the things rooms do to regular loudspeakers. Now contrast that to playing open-baffle speakers in your back yard but sitting really close to them. That's the Raal Requisite difference.

Given the SR1a's speed and freedom from common resonance/compression effects which we habitually interpret as warmth or texture, the preceding amp's 'voice' controls the sound more directly than usual. Typical intermediate buffers or softeners no longer intercede. Now the amp/transducer translation becomes most literal. Here our original Nords had all the right electrical stuff for pennies on our Pass Labs XA-30.8 class A dollar. Just so, they made for a sonically cold clinical non-compelling flat sound to disqualify for this unusual application. After the mod, it was a different story. Now the same amps had tonal substance and material density which on these extreme-proximity off-ear 'speakers' no longer registered as strident, hard or approaching the glassy. Now €3'500 state-of-the-art earfield monitors—that's their registered trademark—could be powered by €1'750 worth of amplification, make a very good impression and not go overboard with heat and size like our XA-30.8 as repurposed for headfi. To get more specific, we of course return to the regular loudspeaker arena.