U2X

Reviewer: Frederic Beudot
Digital Source: Aurender A10 streamer, Lumin P1 mini [on loan], Denafrips Pontus DAC, LHY SW6 Ethernet switch, Jay's Audio CDT2 Mk2, Holo Audio Cyan 2 [on loan]
Analog Source: VPI Scout 1.1,  Zu-DL103 MkII, Genesis Phono Gold
Amplifier: Triode Labs 2A3i, Enleum Amp 23R  
Speakers: Ocellia Calliope .21 Twin Signature, Rogers LS 3/5a, Zu Essence
Cables: Zu Varial, Ocellia RCA cables, Zu Event MkII speaker cables, Absolute Fidelity custom XLR to RCA interconnects
Power Cords: Zu Mother, Ocellia power cables, Absolute Fidelity power cable
Powerline conditioning: Isotek Nova
Sundry accessories: Isolpads under electronics, GIK Audio room treatment
Room size: 18 x14 x 10'
Review component retail: $11'000

From the unredacted audiofiles. "You'd be the first to review it so this would be your scoop. Nothing else like this in the world. MSRP is $11K. Please advise."

"Absolutely. I'd be delighted."

This exchange between Lumin's US importer Source Systems Ltd. and my contributor Frederic Beudot ran under the email header "how about you review this brand-new U2X instead?" Clearly things had gotten reshuffled to present our man with an opportunity he couldn't resist. "Will advise on Monday for choice of finish. We can ship by Monday or Tuesday. It will be time cold and temperature cold so require 150-200 hours to burn." What's 8.333333 days between audio nutters? As a source component not loudspeaker, Frederic could run in Lumin's new range-topping deck 24/8.3 without making one peep. When reviewing from a home shared with a family, such considerations do matter.

What is the U2X? Like nothing in the world according to our US contact. Without stealing from Frederic's thunder, it's the brand's best-ever pure streaming transport to include no DAC but an outboard dual-toroid linear power supply. Socketry highlights are a specially conditioned USB output, fibre-optic networking and clock-sync ports. For more, scroll down for Frederic's content. First a comment from reader and Lumin user Michael: "In addition to access to Amazon Music Unlimited, the recent Lumin firmware offered an under-the-radar filter: the cryptically named QRONO d2a which sounds like a robot from 1950's Science Fiction. Developed by MQA Labs now part of Lenbrook Media Group after its purchase of the assets of MQA Ltd., QRONO d2a applies tailored filters and noise shaping during playback to allegedly reduce timing errors in D/A conversion, leading to what Lenbrook say is clearer more lifelike sound with improved microdynamics and stereo imaging. It works on any digital audio source, making even standard PCM files supposedly benefit from enhanced playback fidelity. As of Lumin firmware update 20, certain models including my X1 now offer optional QRONO d2a processing for playback via their analog outputs." It won't apply to the U2X which lacks a DAC but shows Lumin's constant work on their app. That software aspect isn't visible in hardware photos but a major ingredient of Lumin's digital decks. – Ed.

From first sight, U2X declares itself an ultimate digital transport only so no internal DAC or compromise. As its makers emphasize, this is a pure digital source designed to deliver untouched data to whatever DAC we call ours. Key to that promise are several serious infrastructure choices. The body and external PSU are CNC-machined from solid aluminium billet, a construction method borrowed from the flagship U1X/X1 brethren. The external PSU is a dual-toroidal low-noise linear affair for classic dirty/clean-box apartheid. Connectivity is vast: an isolated USB audio output on a dedicated circuit, coaxial, BNC, optical, AES/EBU plus RJ45 copper and fibre-optic SFP for dual Ethernet with a built-in switch to easily connect one of Lumin's L2 music libraries.

For clocking, the U2X introduces 10MHz i/o with dual outputs so can operate as master clock or slave, offering precise timing for multi-device systems. On the decoding side—or rather, lack of it—U2X can route up to DSD512 and 32/768 PCM; upsample to DSD256 or PCM 384kHz should our DAC or system benefit. I was underwhelmed by internal conversion from PCM to DSD256 when compared to playing a native DSD download of the exact same cut. If you purchase a recording in top quality at Digital Tape Transfer, they let you download all formats, making it very easy to compare identical recordings from the same masters. On Fritz Reiner's 1962 recording of Beethoven's 6th Symphony with the Chicago Symphony Orchestra, internal resampling of PCM 192 to DSD128 sounded notably flatter and narrower than the native DSD download yet neither sounded as dramatic or dynamic as the PCM version. In software and convenience terms, U2X is fully up to date: UPnP, Roon Ready, Qobuz/Tidal/Spotify Connect, AirPlay and Lumin's exceptional Leedh Processing lossless digital volume if you don't want or can't do downstream signal attenuation. I tested Lumin's implementation of this French algorithm with reduced rounding errors in my review of the P1 mini and was impressed with its transparency even at fairly extreme attenuation levels. U2X shared all the same traits.

So on paper, U2X is an uncompromising digital source built with craftsmanship and engineered for purity, flexibility and future proofing. It doesn't flirt with convenience at the expense of integrity but offers a clean slate to build from. Once you hook up a good DAC like the Mola Mola Tambaqui I used for most of this review, the first thing that strikes you is the incremental clarity, the added rightness of the presentation not in a sterile clinical way but as though musical information delivered with a new kind of inevitability. I have heard many excellent streamers and computers including Lumin's own but the U2X stands above them as being clear-cut with more substance and definition, sharper dynamics and more natural ease than lesser transports. It's not like brightness turns up or edges sharpen unnaturally. There is just more to hear supported by impeccable timing. Listening to something rich in detail, say a well-recorded acoustic jazz session or spacious classical track, the benefits become obvious. The soundstage feels wider and more three-dimensional, instruments occupy distinct spaces with more physical presence and there is a sense of air around them. It's not that other transports sound broken. You wouldn't know there was more information to be had without an attentive side-by-side comparison.