The One I've Been Waiting For: NAD's C 658 BluOS Streaming DAC

December 2019

Reviewers' ChoiceMy discovery of NAD’s C 658 BluOS streaming DAC ($1649 USD) marks the end of a very long search.

It began in high school, when I succumbed to addictions to music and audio gear. Ever since, I’ve looked for a device that would allow me to dispense with the ever-growing rack of audio components I’ve set up in -- so far -- 16 different homes. Early on, I had a turntable, tonearm, and cartridge, a phono preamp, a preamp, reel-to-reel and cassette tape decks, a tuner, two power amps, huge speakers, interconnects from each source to the preamp, interconnects from preamp to power amps, and speaker cables -- oh, and a record cleaner. Added to those, following the birth of what Sony was pleased to call perfect sound forever, were a CD player and DAC.

Later additions included regulated power supplies and, eventually, separate dedicated circuits for my analog and digital devices -- not to mention a collection of 13,000+ LPs, 15,000 CDs, and shelves and racks to store them all in. Plus a live-end/dead-end (LEDE) listening room large enough to contain it all, with enough open space between those huge speakers and the side and front walls, and a listening seat at least several feet away from any boundary.

Even the roughest ballpark estimate of the retail prices of all of the above -- not to mention a house that could comfortably contain all of it and us -- will tell you that this was no miser’s pursuit. When we lived in Boston, we ended up just a few blocks from the importer of the small Reference speakers from the Swiss company Ensemble AG SA. These were the first speakers I owned that seemed to completely “disappear” as sources of the sound. I discovered that when I sat closer to the References, the sound and, more important, the soundstage improved dramatically. That’s when I decided to someday find a way to listen to music in the nearfield.

The next step was to try active speakers from ATC. These were way too big for nearfield listening, but at least I could get rid of my garden-hose speaker cables and multiple power amplifiers. This was my entrée to the world of professional gear. About that time, I was forced into an office chair in a bedroom that I used as an office. There I sat all day, writing articles and books about wine. Bingo -- I could get some small, active professional speakers, and listen to them in the nearfield. Also, since I liked to make music, I added a proper audio interface with microphone preamps and a built-in ADC and DAC. All of this was controlled by the same computer that I was using to write my Great American Something. Then I hit a brick wall.

What I wanted was a great-sounding audio interface with multiple analog and digital inputs, as well as balanced outputs for my favored active professional monitors. Then I’d use a Mac for streaming and listening to CDs. There have been many possibilities, from Antelope Audio, Apogee, Prism Sound, RME, Universal, etc., at prices ranging from $800 to $8000 USD.

Then another problem arose. Starting with Audyssey (OK) and then moving on to Anthem Room Correction, aka ARC (superb), I became convinced that any high-end system that lacks room-correction software is like a dinner without wine: possible, but why deny yourself the finishing touch? None of the audio interfaces I found contained built-in room correction. The only other options were outboard room correctors like the Trinnov setup, which costs about $5000 for a 2.1-channel system. But I’d then still need an audio interface and a Mac. A total cost of about $15,000 loomed -- too rich for my blood for an office system. The Anthem STR Preamplifier ($3999) had almost everything I needed, and I love the sound of ARC, which was included -- but I’d still need that Mac and JRiver Media Center or Roon.

Then, a few months ago, the heavens opened. Evidently, the design engineers at NAD had read my mind. Their C 658 BluOS streaming DAC includes every item on my wish list, for a total cost of only $1649 or $1748 (see below). It’s a streamer fed by either wired Ethernet or Wi-Fi, with access to Amazon, iHeart, Nugs, Qobuz, Spotify, Tidal, and some 15 other services already included in its smartphone or tablet BluOS controller app.


The following list of what the C 658 provides is incomplete -- after four months of using it, I’m still not sure I’ve tried everything it can do. For instance, I found out only today that the C 658 can speak to Lutron lighting products. It’s almost easier to describe what it can’t do.

What you get in the C 658 begins with a full-featured, 2.1-channel stereo preamplifier. It has two optical and two coaxial digital inputs, and three sets of analog inputs on RCA, including one set for its moving-magnet phono preamp. That phono section is no afterthought -- NAD has excelled at phono stages since the one in their classic 3020 integrated amplifier of 47 years ago.

Obviously, this is not a pure analog path, and if you want to stick with analog, I understand. But the preamp is so quiet and distortion-free that few will reliably hear the difference. The preamp offers analog outputs in single-ended (RCA) and balanced (XLR), along with two single-ended outputs for subwoofers. Its RS-232 port allows the C 658 to work with Control4, Crestron, RTI, and similar products. The C 658 is made with NAD’s Modular Design Construction (MDC), which helps carry the product further into the future with optional plug-in circuit boards. Available now is an HDMI 4K plugin that lets the C 658 be used with your home-theater setup (albeit in 2.1 channels only); the future will surely hold other fun additions.


At the heart of the C 658 is ESS’s Sabre 32-bit DAC, a very quiet and transparent-sounding chip that can accept signals of resolutions up to 32-bit/192kHz. There’s also a full MQA decoder resident on the DAC. This capability will be vital to those who listen to high-resolution recordings via Tidal Masters.

The C 658 has a very good-sounding single-ended headphone output on a 1/4” phone jack. And if you, like me, have a lot of music files, the C 658 can access up to 250,000 tracks stored on an external hard drive or NAS connected to it.

The included BluOS software can reside on a computer, smartphone, or tablet. BluOS also lets you control and stream hi-rez tracks sent out to as many as 64 speakers all over the house, and even wireless headphones, via Bluetooth aptX HD. If you’ve heard stories about bad-sounding implementations of Bluetooth audio, rest assured that this adaptation is a huge improvement. It can also control devices compliant with Apple AirPlay 2.

I asked Marshall Currier, national sales trainer and technical support specialist for NAD’s parent company, Lenbrook Group, if I’d missed anything. I had. “One other big item is voice control integration,” he wrote. “We work with Siri as well as Alexa and Google Assistant -- provided the client brings their own microphone-equipped smart [trigger] device.” That means a smartphone, tablet, iPod, Alexa, or anything else that can hear and respond to a voice command.

NAD has fit all of this into a case 17.2”W x 4”H x 16”D and weighing 22.3 pounds. And while $1649 isn’t chump change, the C 658 is blessed with sound quality high enough and features useful enough that to call it a stunning bargain is an understatement. Nor is it loaded up with bells and whistles just to please the marketing department. You can use every bit of its power today.


The base price of $1649 includes a version of Dirac’s Live room-correction software with a limited range of calibration. Marshall Currier: “NAD and Dirac worked with our acoustic division [PSB Speakers] on carefully selecting a calibration level [cutoff] which offered a high value to our customers at no upfront cost. This cutoff level was 500Hz, since room gain/interaction is considerable below that range in nearly every common listening room. Higher frequencies [and more listening positions] are offered for an additional cost, but we have found that this full frequency calibration actually can change the voicing of speakers -- sometimes in an undesirable way.” The addition of Dirac Live boosts the sound quality of the C 658 above that of any other current DAC-streamer-preamp I’ve used. Given the state of the art and NAD’s technological heritage, there’s nothing else they could do to a system controller that would give you such an immediate improvement to the sound of your system as the addition of Dirac Live. We’ve been waiting a long time for this combination, and here it is.

So with the base-price C 658 you can get rid of the worst room resonances, but to understand why Dirac Live is competitive with Anthem Room Correction, you have to go the full Monty. Ordering the C 658 with the full version of Dirac Live, as I did and recommend, raises the price by $99, to $1748. Currier has access to Canada’s National Research Council, in Ottawa, one of the finest audio testing facilities on earth, and knows more about this product than any reviewer -- but unlike him, I believe that full frequency calibration is vital to the final product.

The C 658’s sound driving my Barefoot Sound Footprint01 active minimonitors without Dirac Live switched in was very clean and clear. The limited version of Dirac Live included in the base price gets rid of boomy bass. But with the full version of Dirac Live it’s the subtleties that win the day. It may take you some time to acclimate to the new sound, but for me, adding the full version of Dirac Live made a dramatic improvement in everything necessary: timing, pace, frequency response, spatial specificity, the clarity of leading transients -- all were improved. You can try the sub-500Hz version, and determine whether you want to go for the complete version. I think the $99 is money well spent.

Setting up Dirac Live is easy. You can easily use the supplied microphone. It works better than its appearance might suggest. I have the professional Dirac Live setup kit -- with calibrated microphone, preamp, and stand -- that used to cost $250. The difference between using the kit was amazingly small. The whole process took me just a few minutes; the first-time user will probably need closer to 45 minutes.


I’ve developed a real love for the playing of jazz guitarist Bill Frisell. His light touch and willingness to play with silences as much as sounds have a captivating beauty, and it doesn’t hurt that he always seems to work in the best recording studios, as on his recent album Harmony (24-bit/96kHz FLAC, Blue Note/Qobuz). The best distillation of Frisell’s current style is “Lush Life,” here performed as a duet with singer Petra Haden (Charlie’s daughter) and Frisell on Fender Telecaster. As I listened to Frisell’s chiming guitar arpeggios and Haden’s pretty voice, the clarity was impressive. The C 658 reminded me of the better professional audio interfaces I’ve used, such as the Prism Sound Callia DAC-preamp ($2750). What sets the C 658 apart from the far more expensive Callia is Dirac Live. In my listening room, part of a downtown loft, the low E string of Frisell’s guitar can sound a bit woolly -- the fault of the room, not the C 658. When I called on the assistance of the lower-frequencies-only version of Dirac Live, much of that woolliness disappeared. When I switched in the full version of Dirac Live, the imaging, soundstage, frequency response, and clarity all made significant gains.

Harmony was recorded and mixed by Tucker Martine, at Flora Recording & Playback, in Portland, Oregon, where I now live. Martine has worked with Frisell on a half-dozen recordings, as well as with Neko Case, the Decemberists, Iron & Wine, k.d. lang, My Morning Jacket, Beth Orton, R.E.M., Edward Sharpe and the Magnetic Zeros, Spoon, Sufjan Stevens, Jesse Sykes, and Laura Veirs. Those unfamiliar with Veirs should hear her album Warp & Weft (16/44.1 FLAC, Bella Union/Qobuz). The first track, “Sun Song,” offers a gorgeously creamy-textured vocal sound as Veirs shifts between the sweetest pianissimo and much louder singing in the chorus. I get shivers every time I hear this song. She must have gotten shivers from working with Martine. As they used to say when Hollywood was all about glamour, if a star can find a photographer who can capture the star’s dazzling beauty, they should marry. Veirs was smart enough to marry Martine. Through the C 658, the range of subtle shadings of her voice was dazzling.

Recordings of a single or only a few acoustic instruments can reveal every wart in a recording and playback system. Keith Jarrett has a master’s touch when it comes to beautiful sound. I hear a touch of the elegiac in his recent album La Fenice (24/192 FLAC, ECM/Qobuz), especially his lovely version of “The Sun Whose Rays,” an aria from Gilbert & Sullivan’s The Mikado. It’s subtly somber yet hopeful, and though recorded in 2007, it sounds as if he played it last week. The NAD C 658 did a grand job of reproducing the full impact of Jarrett’s touch on his Steinway concert grand.


My last example is one that would have me scratching my head if I hadn’t been there. Marco Paul is a guitarist who plays all over the world and whose long-form video, 24K All You Need Is Gold (check it out on YouTube), has won major awards at the Lower East Side Film Festival in New York and at the Austin Music Video Festival. When some friends brought him over to our place, Marco grabbed my classical guitar and treated us to several songs, one of which I was able to record.

My room has beautiful natural reverb. Marco even commented on the room’s nice sound. He asked if it would be OK if it got loud. I figured he couldn’t get too loud with just a classical guitar, so I told him to go for it. But he was talking about his voice. The sheer power of his vocal crescendos reminded me that no mike can pick up the full power of someone singing fortissimo. I recorded him from 5’ away using my iPhone XR with the full ambient sound of a city loft. I wish we’d had time for me to get out my AKG mikes and get a closer sound. What a gorgeous voice! Next day, I listened to it through the NAD C 658 and my Barefoot Sound Footprint01 minimonitors, and was amazed at the accuracy. Obviously, I was familiar with the sound -- I’d made the recording.

Since their start in 1972, NAD has provided amazing performance for the dollar. But many may not know that they also go the extra mile when it comes to service. Their customer care is quick and utterly dependable. You’ll never hear them point at the other guy and say it’s their fault, just to get rid of you. I’ve recently had major problems with Amazon, Comcast, and UPS, and NAD’s concern for customer satisfaction is a breath of fresh air for someone who’s lately felt trapped in a service sewer.


There are just two things about the C 658 that I’d like to change. While its front panel displays most of the information you need, I wish NAD had provided something like the screen on their Masters M10 BluOS streaming integrated amplifier. And I’d like a balanced (XLR) headphone jack. That’s it.

Remember that huge investment in money, time, and space I described at the beginning? Today, you can buy an NAD C 658 and a pair of good active minimonitors, add Qobuz at its new low subscription price of $14.99/month, and have a substantial system with 99% of the sound quality you could get at any price lower than the apparently unlimited disposable income our friends at SoundStage! Ultra can commit to sound. Buy a C 658 and a pair of professional active minimonitors and you’ll have a great system with its own streaming player, and the ability to play records or hook up a CD player. Control it from your smartphone or computer, and you have music quality that can beat most other systems in the world.

I’m buying an NAD C 658. I’ll use it with a pair of Barefoot Sound Footprint01 speakers ($3745/pair). Thank you, NAD. This is the product I’ve been waiting for.

. . . Wes Marshall