Uff or oomph? At close to $5K, magnitude matters; massively. Prospective shoppers want to know. Does this difference delta split hairs? Is it properly significant? Given elite ancillaries like this pricing game presupposed all along, I found this difference dead easy to hear. As a quasi subcutaneous effect that underlies the actual musical action, it naturally recedes from isolated notice very quickly. It's like a fragrance on the wind, not the visible trees and their dancing leaves and branches. It's less material. It's more moisture in the air without at all becoming greenhouse cloying. One of Dawid's signature words is pigmentation as that which fills out 3D spaces within image outlines. That's FoH's tonal enhancement; more pigment. But the image outlines themselves alter, too. They become gentler so less razor cut. All of it obviously relies on just how much ambient cues a given audio file contains. FoH can't unearth something that's not there. It's why starting with a good recording like Visual 2 is key.

With Palma Audio DHS-1.

Then FoH's addition is surprisingly oomphy. It's a bit like what direct-coupled or ZOTL'd triodes do; without any concessions to noise or bandwidth. Recorded space occupies a broader percentage of the listening experience. That moves away from shadow plays with their black'n'white something/nothing duality. With FoH the apparent nothing of empty space becomes its own far-from-nothing entity. For the right listener, making that dimension of playback more significant could be significant. It's not an additive colouration or trick as might be said for tubes which always do this. With FoH the enhanced spaciousness shrinks or disappears altogether on robotically dry recordings done purely on a computer. Because headphones don't operate in the reverberant milieu of our room, their rendition of recorded space is far more pure. Now maximizing this purity could become a heady mandate for super-serious listeners who've already maxed out their primary playback hardware?

FoH is most definitely not something for nothing. It's very expensive, elitist, esoteric and extremist; the full quartet of potential excess. Yet it does exactly what Louis Motek's award-winning Firewall already does for speakers. It's adapted and repackaged for HeadFi. It's also the cosmetically classiest LessLoss box yet to predictably presage what their existing DAC will eventually look like once it sheds its current more Flintstonian than late Fremen Panzerholz threads. The most appropriate conclusion I can draw returns us to my intro. If Gideon Schwartz did plan on another coffee-table book for Phaidon, on The Most Interesting Hifi Inventions… today's Firewall for Headphones would surely have to feature. As a brief 2nd opinion on Dawid's review to justify my indulging of a personal curiosity, I'm grateful for the opportunity of now having heard this out-there device for myself. It's definitely oomph not uff!

With Soundaware P1x 12wpc class A amplifier.

PS: With my parallel loaner of a 2.5mm/XLR4 terminated C-MARC cable to fit both Susvara and DHS-1, FoH appeared again in my separate cable review…