Although I couldn't get inside my loaner, its ingredients are no secret. Four dual Firewall modules worth $1'600 alone make this a balanced affair. This critical cluster connects to two circuit boards and those to XLR4 i/o via entropic-processed copper rods. The female and male XLR lock in the intended directionality. The passive nature of this tech means that it works without external power. A signal traveling from an amp enters the core Firewall component where it gets conditioned then forwarded to our headphones. That's all there is to it but the devil hides in the details. All parts including the sockets undergo the company's Entropic procedure while their milled brass housing visible beneath the black panels of the outer shell of resin-doused Kraft paper is part of the potent anti-vibration measures which also explain the product's weight. Its satin surfaces aren't regular either. LessLoss have been a huge advocate of Panzerholz known throughout the industry for its superb self-damping properties. The latest Firewall box has all of its six walls built from laminated extremely hard and dense layers of resin-infused Kraft paper which as I'm told even exceeds Panzerholz where it matters. The result feels nice and most definitely like a premium object.

As a passive device that goes between our headphones and amp of choice, today's Firewall was a breeze to use. I don't think I've ever sampled a product easier to dis/engage. It connected to an Enleum AMP-23R via short pigtail terminated with 6.3mm plug on one end, female XLR4 on the other. A headphone cable with a male XLR4 connected this Firewall to a HiFiMan Susvara. I DIY'd both harnesses for this review based on LessLoss entropic-processed C-MARC wiring specifically for cans. Its commercial form is just around the corner. To compare with/out the latest Firewall, I just unplugged both XLR4 from it and then reconnected them so the amp drove Susvara directly. This routine removed any downtime and I didn't even have to adjust volume or move away from the listening chair. Life was peachy.

Again, I'm no stranger to Firewall tech. The more these modules compound, the more their effectiveness multiplies. Think backdrop cleanliness, spatial focus and decay moisture. The first notion of this additive action I had several springs ago upon connecting external Firewalls to Boenicke W11 SE+ floorstanders already fitted with these parts internally at their crossovers. Just one swap with/out sufficed to track meaningful beneficial changes. I enjoyed higher instrumental and vocal hydration, more grounding, rounder less chiselled edges, tighter bass, improved clarity, less grain and images rendered more precisely on a more pristine background. This one sentence encapsulates the general Firewall MO. These are the perks to expect once the Lithuanian inline cleansers are hired to banish transmission noise. In my experience, their efficacy is constant no matter whether they're used externally or built in. The LessLoss tech is the same regardless. To make it more accessible, the manufacturer simply wraps it into several physical forms which competitors can easily fit inside their own products. Boenicke Audio and sound|kaos are two notable adopters with lots of street cred among audio enthusiasts.

Not only do I deem Firewalls very useful with all manner of speakers, I haven't yet encountered one that didn't benefit. The purist rear-loaded wideband breed is known for its direct quicksilvery aroma as much as a somewhat shouty lean attitude that can be shy on bass. To offset that, a suitable amp is a must. More importantly, these xoverless loads are inherently highly revealing by tracking and magnifying even the tiniest changes in our setups more clearly than most regular 2- or 3-ways. Since the Firewalls' arrival in early 2020, I had the pleasure of hosting five different widebanders. Each proved very fond of these accessories with rounder fleshier vocals, a wider colour palette, increased fullness, longer decays, more treble weight, higher clarity, less forwardness, edginess and grit. In my book these devices are free from any sonic downsides – and child's play to use.