Radiation resistance? In prior Amphion reviews with passive rear radiators, I'd heard how indeed, they could be placed closer to the wall without typical ill effects except for the inevitable shortening of perceived soundstage depth. Now the S400 followed suit albeit at different magnitude. With a nearby wall, rear-aimed bass energies see an immediate barrier. This does two things. It increases acoustic impedance and shortens reflective return paths. Closer coupling of moving passive to immovable object increases perceived control over its operating band. Greater breaking power and shorter delays create steeper tautness. Boundary gain adds amplitude so bass-heavy music wins mass but here kick too. Naturally room resonances don't magically vanish. Instead of the hollow bloat of rear ports however, these oval radiators in such close wall proximity increased output then parked more striated wiriness atop room mode peaks. Room resonances thus still telegraphed as a textural difference but instead of being looser and bloomier, it got more wiry. Because the oval Mads radiator is larger than Amphion's, its output gain from this type placement was greater. Critical listeners with some decor allowances will experiment with how increasing speaker distance a bit will impact low-end gains to not overdo them.

On something like Øystein Sevåg's groovy "Seed" from his Bridge album, the robustness and tightness of the low end gained in graceful gravitas and engine-room drive over the upstairs setup. Because these bass amplitude gains didn't come at the cost of control, they enhanced this music rather than sully its high production values. It's important to stress that this did not devolve into a boom fest but rather, celebrated muscular well-endowed bass.

On Eugen Cicero's brilliantly swingé makeover of Tchaikovsk's "Piu mosso" theme from Swan Lake, the sparkling upper right-handed piano exploits which on this lesser recording can veer into the glassy, bright and bell-like still had plenty of zing and pepper to not register as dull or hooded by any stretch.

Only by direct contrast to Ivette's usual Mythology M1 monitors with their planar electret super tweeter would one note losses in airiness and top-end sheen including, on recordings like this, detours into the tinkly and platinum hard.

As I'd already heard upstairs but wanted to confirm before committing to, this Buchardt felt uncommonly sensitive to curtain lift. By that I mean the loudness threshold at which all the colors plus definition and clarity kick into higher gear. All speakers close down and fall asleep if turned down too much. They simply differ about when as one leaves behind rock then room levels to explore background and finally whisper mode. The S400 needs to be played louder than most before all of it steps out of the shadows and into the light. To my mind, this was a byproduct of, or deliberate price to pay for, its meaty darker denser voicing. It's as though on SPL, the higher midrange freqs had to catch up with the bass until they all pulled equally hard. This is a very simplistic description but does track the experience. In short, this speaker isn't a hifi whisperer. It prefers some rein to stretch its legs. Once it does, it's surprising how it keeps scaling up. On that score, it's not really a small-room box. It's a small speaker for bigger rooms where the higher SPL appropriate there will increase its perceived resolution. And I had just the right place and competitor for it. The latter would be Kroma Audio's Mimí. If it sold direct rather than carry dealer and international distributor margins, it would sell for within €500-800 of the Buchardt sans stand. It too is a 2-way with ¾" tweeter, albeit a Hiquphone not SB Acoustics, with a ScanSpeak mid/woofer in a front-ported chemically welded Krion enclosure (a powdered-aluminium/resin composite from the Spanish Porcelanosa company).