To review the D1, I used two systems.
One was an office cellar of 28², the second a typical small room of 6². The cellar is damped heavily, with Goldenote Drums at 40Hz and 80Hz working its frontal corners. The music used was mainly DSD64 - Tubular Bells and Ommadawn by Mike Oldfield, Mondohead by Kodo, Strange Beautiful Music by Satriani and a fair slice of Queen’s discography. Down to business.

The cellar setup consists of the Hegel H160 integrated, Trilogy 992 monos along with matching 908 preamplifier and a laptop with JRiver. D/A conversion is handled by the LampizatOr Level 7 with Psvane WE101D tubes, DSD64 engine and resistor-relay volume module. All of this gear is placed on a Lavardin K-Rak platform. Speakers were KEF's LS50, Xavian's Perla and Gradient’s 6.0 floorstanders. All interconnects were by Forza AudioWorks, the power block was the PF-2 model Gigawatt. Key devices were fed by Harmonix X-DC2F power cords.

In the very beginning, my focus was on the simplest of combinations – the Gradient 6.0 off Hegel's integrated. Both are priced similarly at least in Poland. It's a €5’500 setup excluding cables, platform, power strips etc. The goal was to check whether adding another €2.500—namely the Lumin D1—would change things in more ways than just functional. The Gradient 6.0 are highly resolving, tonally balanced and amazingly spacious boxes by nature. That particular model also sounds very smooth and detailed yet remains effortless to listen to. There's a concentric driver on its front, the same unit which was used in the  Bravo! monitors by Harmonix. Low frequencies are reinforced by an oval passive radiator at the lower back. The Norwegian H160 integrated amp is a transparent beast which adds no colour. Speed and quite twitchy dynamic behaviour are amongst its key aspects. That Norse marriage is overall very likeable. When the Lumin D1 came into play, things were simply getting more picturesque and colourful, warmer and more analogue. Yet it all happened with great proficiency. There was no sleepiness or humidity. The temperature rose to a level which made the three pieces sound more natural and vivid than without the D1. But that was not all.

The Lumin D1 made the soundstage a bit bigger and the layers in front of the listener more noticeable. I had the sense of them being more differentiated. So were the musicians, getting a bit more body but also better stiffer contouring. The bass stiffened up as well which in this particular context was another improvement. The H160 presents music in quite an airy fashion as does the 6.0 by Gradient. The Lumin D1 elevated that aspect further still. Things became even more ethereal and delicate, no brute force in sight. Because that airiness was married to colour, the presentation made for easy listening which I perceived as quite fresh, lively and smooth. With DSD one won't find any sharpness here. Should it happen nonetheless, it's high time to change the recording. It's just not a part of what I heard, period.

After removing the D1, the changes weren't painful but very audible. The bass was boomier and a bit loose but at the same time more fulsome and rotund. Some might fancy that. If someone asked me, I’d call it a quality versus quantity issue. That aside, without the D1 the temperature dropped, a certain matte layering appeared across the audible spectrum and the highs faded to lighter and less pronounced. True, the high frequencies were most definitely there still and enjoyable yet lacked the  weigh and smoothness in play when the Lumin D1 contributed. Detailing suffered as well. To neatly summarize this two versus three box experiment, it's safe to write that without the D1, the sound was more boring. It still was correct and enjoyable and the H160 DAC delivered the needful. Yet something had been taken away and as a consequence, my listening pleasure decreased substantially.