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Synchronicity3. If it takes two to tango, what about three? Unplanned but most fortuitous, the Soloist, Linnenberg Audio u:c:a and HifiMan EF6 showed up within the same two weeks. A friendly showdown was inevitable. For fair play and expediency's sake this particular page would thus feature verbatim in each of their reviews. No need to say the same things three different ways. From this bunch only the u:c:a had a built-in DAC. Hence that became default source for all. Due to the smart 0 marking on its volume control it was easy to set an industry-standard 2V for the Soloist and EF6. This mocked up standard CDP/converter gain to put everyone on equal footing (obviously the u:c:a avoided an analog interconnect).

Source: 27" fully loaded iMac with PureMusic 1.86 in hybrid pre-allocated memory play or
Audirvana 1.3.9 in direct/integer mode with 16/44 to 24/352.8 files
Cables & power: Telos USB, Zu Event signal and power, GigaWatt PF2 power conditioner
Headphones: Beyerdynamic T5p [left] ,Sennheiser HD800 [right], HifiMan HE-6 [on Sieveking Omega stand]

To test raw drive/sufficient gain, HifiMan's orthodynamic HE-6 model (50Ω, 83.5dB) became designated torturer. It wore a 3m 6.3mm-terminated leash from Entreq (syndicated review here). For a high-impedance universal standard I had Sennheiser's HD800 (300Ω, 102dB). Mine are recabled by ALO Audio. I believe an after-market cable is mandatory to hear these at their best. For a sealed low-impedance example I had Beyerdynamic's T5p (32Ω, 102dB) also ALO-ized. These three earspeakers would suffice to keep this joint session tidy.

Entreq replacement harness for HifiMan headphones

When power corrupteth not. Depending on budget, hall and programme, symphonic orchestras may double up. Instead of four French horns there'll be six or eight, instead of two clarinets four and so forth. Even at pianissimo this moves more air. During peaks crests rise higher. Timbres are deeper particularly with more massively paralleled string sections. When the doublers are active during only certain passages, dynamic contrasts widen. Two amps could play the HE-6 loud enough for my ears, the u:c:a maxed out before delivering in full. The Soloist had a goodly number of clicks in reserve. The EF6 was still at half mast. But more relevant with the symphonic image, the u:c:a's forces ran with standard budget numbers. Burson and HifiMan doubled up. The effect on mass, displacement, control, density and drive was unmistakable.

Into this load the u:c:a felt pale, pinched, limp and bleached. Scaled down. Smaller. Far less gripping. Between what were the muscle amps of this bout, the EF6 was warmer, slighter softer and more laid back. The Soloist was clearly crisper, more articulated and forward. Both maximized bass rach and power in ways which are otherwise alien to the HE-6. What is today's K-1000 blossomed under such control like a thirsty plant - except that the real AKG never sounded this dynamic even on the best of days, never mind exhibit such bass.

There was zero mystery to this inefficiency + power = results formula. That's hifi 101. Even so micro-power devotees might suspect the grotesque as though big muscle leads to coarseness and poor reflexes. Au contraire! Particularly with the EF6 the sense of utter command over the HE-6 was coupled to such tangible ease and relaxation as to become true antithesis of anything grotesque. Burson vs. EF6 was the difference between close stage proximity for nearfield transients vs. midfield for a minor shift into greater blending and softer edges. On matters HE-6 the Aussie's €960 sticker was clearly more than sufficient. It made the EF6's $1.600 a more padded bill for those preferring its sonics. The Linnenberg was plainly insufficient. Did the same power equation factor into Sennheiser's high-impedance HD800?

Impossible to know for sure. Yet certain behavior was suggestive. The EF6 made the most robust bass. This lowered the presentation's center of gravity. It and the Burson also staged more widely or lit their performers more evenly side to side. The Linnenberg felt a bit narrower, its lighting more focused on center action. This was secondary however to the deeper black values of the EF6 and how those infused the general color palette with more overall richness. On the HE-6 the score had been 2:1 (EF6/Soloist vs. u:ca) to focus primarily on suitability. Here all three amps were equally suitable. The grouping had simply shifted 1:2 (EF6 vs. Soloist/u:c:a) and now dealt in flavors, not raw drive sufficiency.

Fanciers of the Audez'e LCD-2 tend to find the HD800 too flighty and top-heavy. They would have found that the 800/EF6 combo brought the presentational style far closer to their ideal, albeit with still more treble extension and energy and less bloomy bass. By comparison the Burson and Linnenberg zeroed in more on Sennheiser's brisk treble and presence energy for a higher acoustic center. This affected posture (relaxed: wiry/jumpy), articulation (soft:sharp/crisp), tonal hue (dark:light) and texture (wet:dry) all 1:2.

Aside from sounding less grippy and more relaxed and grounded, the EF6 had a measure of what valve aficionados call moisture. That points at more highly audible reverb action or wetness. Its classic counterpoint is the transistor trait of focusing on the leading edge instead. In this lingo that becomes the dry polarity. This shift was mild but present. The drier readings of the Soloist and u:c:a stayed well clear of feeling overdamped and the reading of the EF6 wasn't fuzzy. Thinking of the latter as a gentler giant and the other too as the friskier smaller operators catches the drift. Über power as mellowing agent perhaps?

Definitely. The sealed T5p's native bass response is powerful and extended already. By itself this accounts for the grounding action which the HD800 required and maximally got only from the EF6. Now both u:c:a and Soloist wrought the tauter energetically more gathered and grippier presentation from the Beyers. The HifiMan amp felt nearly too relaxed, its metronomic heart beat slower as though not fully committed. Ease turned nonchalance. The sense of focus and forward momentum was greater with the other two. This inverted the prior Sennheiser score 2:1. The T5p clearly enjoyed the most efficient power transfer of the bunch to play loud with the lowest volume control settings. This seemed to disadvantage the HifiMan.

Whilst risking to overdraw, here the EF6 felt a bit like a cubic monster engine outside its ideal torque window; or cruising at highway speed in high gear/low RMP where a downshift would get the sportier revvier response. I quite preferred the physically smaller amps on my Beyerdynamics. The big amp had ruled on the Sennheisers, the HE-6 saw mostly a draw between Burson and HifiMan. This was an unexpected and thus twice opportune reminder of that old saw right tool for the job. A universal excellence machine that scores an ideal 100 into each and every load remains quite the rarity.