Nip 'n' tuck. Once I added the sub with a 50Hz low-pass and 6 on the gas, I had perfect sonic normalcy and complete bandwidth. That low-pass usually sits at 10Hz when the Zu is meant to sneak in below 30Hz. It gives a bit of extreme low-end massage for the majority of our resident speakers. Remember that a 4th-order filter isn't a brick wall. Audible sound bleeds past/above the figure on the dial. If you want an actual handover at 40Hz, selecting that number could be too high. It depends on the main speaker's rate of bass attenuation. It depends on where/how your room adds its own gain. My new value demonstrated how much help the Czech boxers could take. Cranking the attenuator up from its customary 2 spoke further to that. But, it was due also to the Evolution's 96dB sensitivity. Appropriate room levels meant a lower position for preamp volume. This sent less signal to the sub to require compensation. Still, some of the difference was due to just how much bottom end could still be built out. I now had a 3-piece ~€17'000 speaker system (€12'000 for the Evolution + horns, €5'000 for the sub, still add some for additional power cord and interconnect to the sub). This was costlier than our various resident boxes except for the German Physiks HRS-120. Just so, this now had its very own particular flavour, distinct from our usual options. On a side note, the Evolution's lack of bass at the listening chair made adding our sub dead simple. I had to contend with far less unwanted overlap relative to an ideal analog low-pass value. This gave the sealed Submission more room and bandwidth to strut its stuff without unwanted side effects.

Now think about the short horn's gradual transition of driver to room air. It suggests a quasi 40cm circular sound source as the wooden guide's mouth diameter. Then add the primary (rear) horn's even larger rectangular mouth. The upshot of both was an undeniably big sound. Have you compared life sound between amplified and unplugged gigs? In one corner, imagine a 7-head Andreas Vollenweider crew at the Montreux Jazz Festival. Each performer is fronted by at least one microphone and a mixing engineer controls their outputs into PA speakers from a console at the rear of the audience. In the other corner is Hariprasad Chaurasia's son playing Indian bansuri flute. He is accompanied by four percussionists during Divali Festival in Pully. There's no microphone in sight. It's au nature versus electronically amplified. With the latter, images of singers and instruments are larger than their actual creators. Each sound source puffs up into something more amorphous than finely chiseled. Purely acoustic performances throw smaller more defined images. Modern hifi with its small-diameter hi-tech drivers makes them even smaller and more tautly focused yet. In general, amplified music is also bass heavier and thicker. Purely acoustic music gets leaner and contains more HF energy (though some of it depends on the instruments and your distance to them). Most modern hifi has far higher treble content than any life concert I've been to.

The horn-fitted Evolution was closer to amplified live sound: generously sized, loose not stretched tight, without hifi's edge-limned separation but instead showing softer transitions. Decays on HF content were shorter than with our usual Raal ribbons, Accuton domes or electrostatic super tweeters. This meant diminished air and less champagne fizz. The treble was drier and harmonically less explicit. This impacted the recreation of recorded space. I had less spiderwebby recorded reflection markers with which to map out the venue for a mind's eye walkabout. Audio talk refers to this as "they are here". It's the meat 'n' potatoes reality, not the time/space traveling "I'm there" (looking in on the recording booth or mixing console). In our 90m² space with gabled ceiling, this wasn't a super-delicate maximally finessed sound. This was freer; less fussily sorted and focused down. Our playback venue was also more capacious than RDacoustic's Munich demo space. This should have been less than ideal for how the Evolution's rear horn is supposed to couple to its environment.

My last adjustment to cancel out first impressions was an amplifier swap. The 10wpc FirstWatt SIT1 monos made room for their 25wpc F7 stereo cousin. As I'd learnt with Martin Gateley's soundkaos Wave 40 (a 93dB widebander with Raal ribbon) and even with Sean Casey's Zu Druid V, some widebanders mostly not of the 100dB kind appreciate more power than their efficiency predicts. So it was with the Evolution. The more potent stereo amp outmuscled and outbodied what became clearly slimmer more ethereal monos into this load and room. Having played out my musical chairs routine to progress from ugly duckling to swan over the course of just a day, I was ready to dig into final sonic impressions. I now had a fair not handicapped sense of what the RDacoustic Evolution could do. Documenting how I got there simply kept it real. Some audio bliss isn't about instant gratification. It's about adjustments and a learning curve.

Indirect contrast. Having reviewed then owned the Voxativ Ampeggio, reported on the 9.87 Pi system; having heard Ampeggio, Voxativ Dué and 9.87 at a friend's many times over... this Fostex clearly wasn't as illuminated or fast; not that I'd heard this driver before. Of course my active bass add-on contributed serious counterweight. But even bypassing Zu's 12" woofer, the Fostex with/without Oris 500 had the less developed treble. Together with its big point-source effect, this made for a rich very substantial midband of the "music lives in the midrange" type. It's what bandwidth-challenged valve amps do by default. Except here it came off with actual infra bass.

In many ways, this was the sound of a 12" widebander of perhaps legacy Tannoy stripes; if one replaced their dual-concentric tweeter with a whizzer. It was slightly dark, chewy, with loads of tone density over ultimate detail magnification and no upfront shenanigans of shouting Lowthers. Unlike Heco's 2-way Direkt with 10" Kraft paper woofer, downfire ports and hornloaded tweeter, the Evolution's gestalt was less damped, less cracking and more billowy. The same would be true versus the Zu Druid V's hard-hung 10.3" widebander. That's tuned for decisively more shove, crack and kick especially in the vital upper bass range. Aside from punchier damping however, the Direkt and Druid would be distant relatives to the Evolution on full-fat tone if not on Rock-ready attitude.

Certain 100dB models including Rethms champion a maximally laid-bare aerated presence zone. They are ultra informative to come on song very soon. That's because human hearing is most astute between 1-6kHz. Here the Evolution's less extreme resolution and lower efficiency took more SPL to show up. Even so low-level satisfaction was good given the generous sizing and deep tonality. Things never got threadbare as though going nowhere fast like a poorly done Lowther clone. There was no steely stridency, no whitening bleach. This driver seemed tuned to relinquish a bit of incisive detailing. In trade it didn't get frisky on hot overcooked stuff. In short, here it acted as a tamer mellower rather buxom ambassador of the breed.

Detractors of course claim that widebanders fall apart on complexity. They're good only at pipe'n'slippers stuff; the boring tunes old fogies listen to just before they cast off their mortal shellac. Only big multi-ways can call Bruckner's 9th Symphony without getting a busy signal. One driver, never mind its ultimate bandwidth, can't track the multitude of dynamic challenges at work in big works. That's what they say. Of course this also depends on just how loud you push things and whether silly cannon blasts, submarine missiles, T-Rex stomps, Kodo drums, Yello-type disco beats and other long-throw badness factor. And, what feels loud and low in a small room could feel luke warm in a really big one. I'd certainly accord a conventional 4-way speaker far greater dynamic linearity potential to scale up evenly across the range without compression or cone deformation, i.e. not have the lower end lag more and more behind. The question is, does this play out at volumes which folks use in rooms of average size in the real world? Or is it more of a theoretical concern? To check in on that, I deliberately cued up some thumpy French/African rap by Daara J; some colossal Janáček; some fiery Ibrahim Maalouf brasses; and brutal slap bass. Since I ran the Evolution unfiltered, any misbehaviour on the Fostex would show up as distortion regardless of the Zu sub's stoic underpinnings. But I also double-checked with the sub turned off to be sure. All I can report is that at SPL our household considers loud, I heard nothing amiss which stood out as any particular shortcoming to not play such music again. I have to leave discussions on Doppler distortion and other imaginary widebander ailments to the armchair experts.

Which gets us at the inevitable "widebanders luv tubes". From experience I'd concur that the 100dB brigade does very often sound better with valve amps. In the 93dB realm however, I've come across a good number which sounded as good or better on the right transistor amps. Instead of speculating over the why, I'll simply say that I found the Evolution to work better with the FirstWatt F7 than S.A.Lab Blackbird SE. With its already billowy behaviour, the transistors tightened the ropes on those filled sails to go faster. But I did have small-signal tubes in the DAC and preamp (Aqua Hifi and Nagra respectively). Suffice to say that like the soundkaos Wave 40, the RDacoustic Evolution worked well with 25wpc FirstWatt amps. I'd expect a Clones Audio 25i to be another good very inexpensive match. For a lot more coin, the 15wpc Bakoon AMP-12R was terrific. In fact...