Aero

Reviewer: Frederic Beudot
Digital Source: Aurender A10 streamer + Denafrips Pontus DAC, LHY SW6 ethernet switch, Jay's Audio CDT2 Mk2
Analog Source: VPI Scout 1.1,  Zu-DL103 MkII, Genesis Phono Gold
Amplifier: Triode Labs 2A3i
Speakers: Ocellia Calliope .21 Twin Signature, Rogers LS 3/5a, Zu Essence
Cables: Zu Varial, Ocellia RCA cables, Zu Event mkII speaker cables
Power Cords: Zu Mother, Ocellia power cables, Absolute Fidelity power cables
Powerline conditioning: Isotek Nova
Sundry accessories: Isolpads under electronics, GIK Audio room treatment
Room size: 18'x14'x10' 
Review component retail: $3'950

Foreword. Aerotic? If you know the Berning/LTA connection, Linear Tube Audio's Aero DAC goes off-script by being a single-ended not push/pull circuit; by avoiding coupling caps; by being first to offer XLR outputs which combine two single-ended paths each; and by not being a pre-existing Berning circuit. There never was a Berning DAC before. If we're looking for erotic friction, we could cheekily say that it's a new Kamasutra position in the good Book of ZOTL. It's also an R2R DAC, albeit not discrete but based on the AD1865 chip. This next Aries Cerat Kassandra Ref II valve DAC champions it as well; 12 per channel in fact. But then it costs 15 times more yet does not have the patented Zero hysteresis Output Transformer-Less aka ZOTL circuit which all Berning kit applies to its tubes.

Audio Note too ran this chip in a €50K DAC so amongst brands promoting an 'analogue' or 'un-digital' sound, it's well regarded.

Early Aero prototype.

This inside shot of production Aero shows 300'000µF capacitance. The red board is a Serce¹ module from Poland's HEM, parent company for Ferrum Audio of Wandla fame. That module can handle USB, digital signal routing even I/V conversion. Aero obviously is no DAC with generic tube buffer. Neither does it look like a classic valve circuit. It's the creature from the black ZOTL lagoon that doesn't do MQA, DSD, I²S, AES/EBU, negative feedback, Windows drivers, signal-path caps or anything beyond 192kHz. It plays a different game than buzzword compliance or spec wars. Even its power supply is an amalgam of linear and switching tech. This creature has definitive features. They're just different from the norm to aim at another audience than the ESS brigade. It's precisely why Frederic signed up with his vinyl front end, Denafrips Pontus R2R DAC, Enleum AMP-23 replacing an exotic 2A3 SET and Ocellia speakers with PHY widebanders and dual super tweeters. I'd written this intro when it seemed that I was booked for a 2nd opinion to his review. When loaner allocations changed, I decided to let it stand for his benefit. Over to you, Frederic.

¹ From my Wandla review: "Who/what is Serce? 20 years of digital experience pooled into an ARM Cortex M7 processor on a red 5x7cm PCB is what. That routes USB, S/PDIF, AES/EBU, differential I²S over HDMI or RJ45, ARC under CEC control, MQA and infra-red remote code. Serce disavows reliance on critical 3rd-party silicon which the pandemic showed can end up seriously back-ordered; or have remaining stock sell at inflationary pricing or high-volume ransom. With Serce key routing and processing happen in custom code owned by HEM. Actual conversion still happens off-board with a designer's choice of favoured chip. Combining the functionality of usually five big IC into one has Serce benefit manufacturing ease and shorter signal paths without redundant signal routing/reflections from chip to chip. DSP no longer interferes, even power consumption is less. For Wandla this allowed Ferrum to implement digital filters beyond the stock ESS options for superior stopband attenuation, upsampling algorithms, interpolation and I/V conversion. Ferrum are particularly proud of their current-to-voltage converter. It undermines myopia that converter silicon cements sonics; or that only the analogue output stage and power supply matter. As Ferrum explain, how one pre-conditions digital signal before it hits a converter chip is very important, too."

… to be continued…