Bent Nielsen's final word remote is what makes Aavik's active filter module one of a kind. Being able to change filter freqs between 60 and 160Hz from the seat whilst remaining purely analog is unique to my knowledge. The active crosssover concept per se is very far from. My icOn Gradient Box does the same. It even adds a remote-selectable shelving filter for +3/6dB lift at 20Hz starting at 80Hz; and instant bypass. What it can't do is switch its frequency options by remote. There it goes manual. Here Aavik hit the next level; and build it into certain models to avoid a spare chassis, power cord and set of cables. Unlike my Gradient Box's 4th-order Linkwitz-Riley slopes for both high/low pass, Aavik combine a 4th-order low pass with a 2nd-order high pass "for smoother phase transition". The low-pass level can adjust in 0.25dB steps across a ±6dB range. Are you no fan of filter fun? Don't participate. Save yourself €4'000. With the C-280 you still get a 5-input 2-output preamp with remote and the firm's signature high-density fiberboard enclosure painted black. Given my Darko poll entry, the filter's appeal simply seems high when an unexpected number of people run subwoofers. Shouldn't they have superior integration tools?

Prolonged bass signal at high SPL heats up the voice coil of a 2-way monitor's mid/woofer. That increases its impedance so chokes dynamic contrast all the way up to ~2kHz where that driver meets its tweeter. Remove bass stress and dynamic range/ease increase across a very broad bandwidth. Ditto for reduced excursions creating less distortion. One simply needs to actively filter the mains. So the 'C' in C-280/580 is short for control. The 'P' which might have abbreviated preamplifier already prefixes Aavik's power amps. In their lingo, a preamp is a control amplifier. Once we add the filter module, what we control increases in scope. Now we can think of C². Be in control, totally. The full dose of vitamin C? We just know that's good for us. Before casual phrasing gets us into technical trouble, most rooms have three primary resonance modes set up by the dissimilar distances between front/rear, side/side and floor/ceiling surfaces. Lesser oblique modes run diagonally between corners. A twin-slope filter obviously has just one inflection point not three. It can only address one room mode, not magically eliminate all three. In a square room two modes occur at the same frequency to become one mode at twice the severity. Should the room be a perfect cube, we're down to one core mode that's aggravated to the extreme when its resonance triggers.

Should we pick the C-280 filter's highest 160Hz option, we might want twin subs for upper bass in proper stereo. At ~100Hz and below, my experience says that mono bass doesn't really betray itself. Also, many modern subs use DSP to build in EQ and general bass linearization. Most allow us to bypass their internal low pass; or feature a discrete LFE input which anticipates being preceded by an HT pre/pro's bass management to omit its own filter. Just so, the rest of its DSP remains in play. If we value time alignment, the onus is on us to inquire about sub latency. That of my upstairs Dynaudio S10 is 2.5ms. Sound travels ~1m in 3ms so this delay equates to parking the woofer ~0.8m behind my speakers. I compensate with the exact inverse. Park the sub about 80cm closer to the seat. Time alignment restored. Bass which arrives even just a bit late is slow by definition. Just imagine parking the sub in one of the front corners 2 meters behind the speakers. Not in our digs!