As We See It

I recently received a letter (not yet published) suggesting a need for a glossary of newer hi-fi terms (footnote 1). Some audiophiles raised on physical media, it seems, are perplexed by descriptions of the new streaming landscape. Just yesterday, all we had to worry about was DACs and transports. Today we have servers, streamers, players, streaming DACs, and all that. That immediately struck me as a good idea, allied with a second reason: To avoid confusion, it makes sense for the industry to standardize the nomenclature. When we see the word "streamer," for example, we should all be thinking about the same thing.

So, here's a brief glossary of streaming-related devices. The goals are twofold: to explain some of the newer terminology for those who haven't yet mastered it, and to encourage consistency in how the industry describes streaming components.

I'll start with the low-hanging fruit, which also happens to come first alphabetically.

Digital-to-Analog Converter (aka DAC, D/A Converter, or D/A Processor): This, surely, is understood by all, as the device that turns digital music data into an analog electrical signal that, when amplified and sent to loudspeakers, is perceived by the ear as music. One small bit of ambiguity remains, however: Most DACs contain integrated circuits that do the actual conversion. It's acceptable—not wrong—to refer to those microchips as DACs, but it can lead to confusion: "What DAC is in your DAC?" So, in conversations related to audio components, let's call those special microprocessors "DAC chips."

NAS: NAS stands for "network-attached storage." Because I would never write "a storage," I like to add "device" at the end: "A network-attached storage device." A NAS device is simply a file server with an IP address and an Ethernet (and, often, Wi-Fi) connection, which makes it accessible via the local network. It's a good way to store and retrieve massive amounts of music data.

A NAS device has advantages over other, more local types of storage. It's cheap. It's easy to automatically back up a NAS device to "the cloud"—that ephemeral network of distant NAS devices. A typical NAS device uses a common protocol—RAID, for redundant array of independent discs—to create redundancy, providing a measure of data security. My NAS, for example, includes 20TB worth of storage in four 5TB hard drives, resulting in (I believe) 10TB of redundant storage. If any single disc in my NAS fails, I can pull it out and replace it with no loss of data.

Player: Like "transport" (below), a player can take various forms. A player plays music. Its data source may be onboard (SSD or disc transport) or off (an Ethernet/ Wi-Fi renderer delivering data stored on the internet, or a NAS device). What makes it a player is a DAC and an analog output you can send to a preamplifier—or if the player has a volume control, directly to an amplifier.

Server: In the purest sense of the term, a server is a storage device, delivering data from its own internal hard discs or SSDs—nothing more. It may deliver that data over the network—so, a NAS is a server—or a local connection (USB, S/PDIF, etc.). Common music servers include the Innuos Statement and Roon's Nucleus.

Strictly speaking, that is all a server does, though it makes sense these days to combine a server with other capabilities, like a streamer (forming a server-streamer) and maybe also a silver-disc spinner to form an all-purpose transport (see below). A server that is also a player—that has a built-in DAC—would then be called a server-player or server-DAC (you choose). Add in a network streamer, and you've got a streamer-server-DAC.

Streamer: The most ambiguous term in our glossary, "streamer" is commonly used in two different ways. Too commonly, the word "streamer" is used to describe a player (see above). That's no sin; it's just imprecise, or anyway, inconsistent with my formulation. Let us all settle on this definition: A streamer takes data from a network—via Ethernet or Wi-Fi—and delivers it to a DAC. The data may be local—served up from a NAS device (see above)—or it may come in over the internet, from Qobuz, Tidal, Spotify, and so on. A streamer's output, then, is digital, delivered via a local interface (not Ethernet or Wi-Fi).

Transport: Traditionally, a transport was a device that spun silver discs and extracted the data for processing by a DAC. It could refer either to a separate component, with digital outputs, or to the part of a CD player that performed this function, delivering its data over I²S to a built-in DAC. In the streaming age, it makes sense to generalize the term, to designate as "transport" any device that renders data for D/A processing, however or wherever it is stored. A streamer, then, is a form of transport, as, of course, is a silver-disc spinner.

I have often wondered why our world does not contain more all-purpose transports, combining a disc spinner, digital storage, and streamer.

Any of the above may be combined with other components—for example, you can add a streaming DAC to an integrated amplifier to form a streaming integrated amplifier, or to a preamp to form a streaming preamplifier.

So what did I miss? Let me know, and I'll be sure to include it in a future update.

New Names
This issue has two new names on the masthead. First comes Jason Davis, a talented writer with a talented set of ears, as Contributing Editor, Audio. Jason has previously written two short essays for My Back Pages, then he wrote the New Noise column at Positive Feedback. This issue includes his first Stereophile review, of the Rogue DragoN hybrid (tube/class-D) monoblock power amplifier.

Jason brings several valuable things to Stereophile: relative youth, an appreciation for value, and taste in music that's rather different from that of Stereophile's other writers (Agalloch, anyone?). Check out the review.

The second new name on our masthead may seem familiar. Mark Henninger is the editor of Sound & Vision, Stereophile's sister publication. He joins Stereophile as managing editor while continuing as Sound & Vision's editor.