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When Wei's USPS tracking number showed a lengthy languish at Swiss customs, my downstairs mailbox held the key. Swiss Post wanted to know the shipment's value before releasing it. I wrote what I reckoned was dealer cost and returned their form by snail mail. When I checked with Wei, he'd declared 1/100th of the sell price reasoning sample status made it so. No wonder customs raised a flag. The weight and size of the shipping box alone told a different story. Duly suspicious a visual inspection then divulged clear luxury goods inside. Quarantine until true value was submitted. Cost of the inspection? 13 Swiss added to my 13% VAT cash payment to the driver. That paid for the 'samples' six times over. Such can be the pecadillos of reviewing across international borders. And I was keen on getting cracking. The German Physiks 87dB HRS-120 omni widebander with downfiring 10" woofer still in for review suggested it might be an ideal Sopranino candidate including its circular flat top of appropriate size.

Why did I think the HRS-120 ideal? Radiating a true 360° across its 40-21.500Hz bandwidth, it activates the room's own ambient field like real performers would. Reflected sound dominates direct sound. The upshot is image lock less specific than with conventional tweeters' beaming dispersion. Adding to the German's tweeter-thru-upper-bass omni a directional forward-radiating HF unit might graft atop it more conventional image specificity. If I rolled it in at its lowest 8kHz value. That at least was my assumption. I was curious whether it'd hold.

First an obligatory reality check. Subwoofers and super tweeters afford us bandwidth education by turning off the main boxes. If you're the slightly obsessive type, this exercise could be a bit of a cold shower. Did you expect this little stuff to happen below 30Hz and above 10K? Here we must still account for leaky crossovers. They act as anything but brickwall filters. The majority of the little stuff you'll hear with just a super tweeter connected is actually attenuated data from two octaves below its presumed bandwidth. A 50dB/octave or steeper filter would be more telling but those don't occur in the analog realm. It'd simply hammer home that anyone above 50 with decent hearing—call it ~15kHz—will be hard-pressed to shell out $4.000 or half that or half that again for a super tweeter of any persuasion if that's all you were wired up for.

But we're not dealing with brickwall filters. Far from it. Hence there's overlap into the presence region. And that's audible. Does that make a super tweeter into a specialized type of HF tone control? For now we'll return to the German Physiks omni. A few things became crystal quickly. To get audible and sufficiently assertive over the omnipolar treble energy, Sopranino insisted I run the HRS-120 at -2dB rather than +4dB on its treble contour; set itself to full rather than half-power gain; toe it in to fire directly at the seat; and tilt it down with a rubber bumper beneath its back edge to align with my ears on that axis too. Visually I'd have much preferred Sopranino without its tall glass box from which it suspends cheek to cheek via small protrusions set into cutouts in the glass. Absent that option I eventually turned Sopranino into Oninarpos and upside down. 
Still right side up as most would probably use it.

Rather than a shift in tonal balance we'd expect and get from a tone control, Sopranino in this very unusual combo with a full omni did two things that were rather more subtle. It increased airiness—this differed from album to album—and heightened performer outlines or what we might call the degree of lock on image fixation. The former factored in purist recordings with keen audible space from venue reflections. Those visual/contextual cues became a bit stronger yet receded to insignificance with overproduced studio fare. Image specificity gains remained consistent regardless of production. This again was a more feeling-inquiry 'visual' thing than hard audiophile quality.
Oninarpos in action.
Had I expected higher harmonic sophistication—the Sopranino's bandwidth doesn't really deal in fundamentals—I'd have been disappointed. Where the HRS-120 outdoes any front radiator is quality of tone. That's entirely disassociated from amplification choice. It's about involving the entire playback venue to arrive at the ear as a preponderance of reflections just as a real performer would in the same space. It's the antithesis of lean dry bleached hifi sonics. It's juicy, redolent, wet and tunable by changing boundary distance. After listening in enhanced mode for an hour, I reverted to the HRS-120 solo. Contrast by subtraction definitely registered. But on well-considered balance I favored the sound sans Sopranino for being more natural and easier. The Sopranino injected a whiff of the spectacular. With it came a shift in listening attitude. I no longer followed the music groove like a bit of drenched driftwood. I was actively riding it. That's a different internal focus of attention. As such it's mighty difficult to convey. Let's just say that the whiff of the spectacular felt less organic. It was a bit like Photoshop's sharpen command. On its own it's impressive. Compared to the original photo if you still have it—and if that was in proper focus to begin with—it's pushed. And the HRS-120 had my vote au nature, not pushy. Sopranino also sorely Frankenstein'd the Germans' clean but already tekkie-top cosmetics. But that's arguably a different subject. Personally I'd lose the bling glass case which unnecessarily increases height. That'd make the super tweeter more compact and just a tad stealthier.

Less relevant than my preference was the fact that Sopranino set up properly did something. In degrees of magnitude and with this speaker it belonged to the realm of Franck Tchang resonators, Schumann synchronators and similar. With that established as a starting point, 'twas time for musical chairs. My flat-topped Boenicke Audio B-10 in the upstairs system were next. Their concept, if not entirely conventional, is certainly closer to a standard speaker than a German Physiks to make for a more representative stand-in. Much in hifi is about trial and error, learning curves and experimenting without pre-commitments to outcomes. The B10 already might be a more suitable soprano for Sopranino augmentation. If not I had another floorstander on hand and more inbound.