Digital Processor Reviews

This paragraph from Linear Tube Audio's website description of their new Aero DAC sets the tone for the story I'm about to tell. "After trying various options, we chose the Analog Devices AD1865 R2R DAC chip, which is sometimes called the 'vinyl DAC,' for its organic sound. It is a non-oversampling DAC, with no digital filters. The AD1865 is much-loved by audiophiles and is used by at least one hi-fi company in a flagship DAC costing over $150,000."

Check the forums and you find that the AD1865 chip is also a heavy DIY favorite. Home brewers are attracted to this discontinued, "obsolete" 18-bit chip for its easy implementation and unprocessed, music-friendly sound.

A few summers ago, I briefly got it in my head that I could become a wine connoisseur. This was due to a very generous and unexpected gift. A local acquaintance had passed away, and his wife wanted to rid her basement of his small wine collection.

I don't know why I was chosen as the lucky recipient, but after stammering half a dozen thank-yous, I suddenly owned about 150 fine wines. A few carried four-figure price tags.

Reliably telling a Pinot Grigio from a Chardonnay isn't part of my skill set. Grape varieties, terroir, vintages? You might as well ask a toddler to become conversant in quantum mechanics. Still, I was intrigued by the bottles and amused by the ridiculousness of the situation. Me, an oenophile? I supposed I could pretend, and I did.

After opening and drinking, with my wife, a 1988 Château Léoville Barton, I wrote an over-the-top review and emailed it to a wine-loving friend for his amusement. "I beheld Hawthorn berries and beef stock along with a suggestion of blonde tobacco. Other than the obvious green walnut, there was a top note of wet Baja beach at dawn, mixing subtly with minke-whale flatulence and a hint of two-day-old scallop innards. Finally, with subsequent sips, I detected the aroma of the well-worn merkin of a Honduran sex worker. All in all, not a bad wine."

Eat your heart out, Robert Parker!

For music listening circa 2024, streaming is both the present and the future. Physical formats are still around, and they are still the best choice in some cases, as with deluxe reissues of beloved albums, which may add value with extra live performances, full-resolution surround sound, and other perks. The niche vinyl market continues to thrive, and that business model obviously works for releases of a few thousand copies. (It also works, apparently, for releases of hundreds of thousands of T-Swift platters to be displayed on shelves and hung on walls.)

But facts is facts: Streaming is now the only mass medium for listening to recorded music—the primary carrier for music—and has been for a few years now. According to RIAA statistics, the crossover year was 2016. That's when, in revenue terms, streaming outpaced physical formats. By 2022, the latest full year tabulated, streaming accounted for 84% of US recorded-music revenue.

So what's a long-time audiophile, born into the analog world, with strong roots in physical media, supposed to do?

One thing that interested me about the StormAudio ISP Evo is that, despite its obvious hi-fi function, it's more like a computer than a typical "prepro." While it does offer a few "legacy" analog inputs, it is for the most part all-digital, input to output, including network connections on both ends. Consequently, it is less likely to leave sonic fingerprints on the music than devices that convert digital to/from analog or modulate their signals with active amplification or attenuation. It is notable that, despite its audio function, the Storm completely lacks traditional audio specifications—distortion, dynamic range, and so on.

Yes, that aspect of the product was appealing, but the real trigger for me was that when I began this review, the StormAudio ISP Evo was the only consumer device to fully incorporate the latest version of Dirac Live Active Room Treatment (ART).

When standalone digital/analog processors made an appearance a quarter-century ago, they were limited to the CD medium's 16 bits of resolution—at best. These days, almost every DAC can process at least 24 bits, and many models offer between 20 and 21 bits of real-world resolution. Modern models from Benchmark, dCS, , Merging, Mola Mola, Okto, and Weiss illustrate not just the skill of the circuit designer but also that of the engineer who laid out the printed circuit board.

One of the first digital processors I encountered that offered 21 bits of resolution was the Weiss DAC202, which Erick Lichte reviewed in January 2012. Subsequent processors from this Swiss company have consistently performed well, not just on the test bench but also in the listening room.

Three products were recently subjected to second opinions: I reviewed the revised RS250A version of HiFi Rose's RS250 streaming D/A preamplifier and the optional DC1 DAC module for Audio Research's I/50 integrated amplifier; Ken Micallef wrote about his time with the Volti Razz loudspeaker.

I've been running a 5.1 system for years. Recently, I expanded it to 5.3 with the addition of two more subwoofers. This system is manageable with one of my eight-channel DACs.

Even more recently, I dipped my toe into Dolby Atmos, which made it necessary to lash up at least four more channels. That was a big problem, since neither JRiver nor Roon can support and sync more than one output device at a time, and the multichannel DACs I already owned tap out at eight channels.

I turned to the Arvus H2-4D Renderer, which offers 16 channels of digital output over AES3 and 16 channels of balanced-analog output. This worked, but piping everything through the Arvus meant forswearing DSP, including DiracLive. I really needed a DAC with at least 12 channels.

The Merging+Hapi has been around for years...