NAD Electronics

C 658 BluOS Streaming DAC

AUD $2,599 / NZD $3,499

NAD Electronics has been producing affordable, quality hi-fi since the late nineteen seventies, having made its name with the iconic 3020 integrated amplifier. Now owned by the Canadian Lenbrook Group, it’s a stablemate of PSB loudspeakers and Bluesound – more of which later. The C 658 that you see here is a do-it-all streaming preamplifier that very much follows in the company’s affordable audiophile tradition.

Although notionally a preamp, it can also be used as a standalone network music streamer. You can connect it to a power amplifier or active speakers with a choice of balanced or unbalanced outputs, and there are two RCA analogue stereo inputs, plus two TOSLINK optical and two coaxial digital inputs. There’s a subwoofer output with adjustable crossover for bassheads, a moving magnet phono stage for analogue addicts and a Type A USB input for computer audiophiles. Twin expansion bays allow for potential upgrades, meaning the C 658 is more ready for the future than most.

Being a network streaming device, there’s an Ethernet port for a wired router connection, plus dual-band Wi-Fi for wireless linking. There’s also a two-way aptX HD Bluetooth function which allows you not only to send audio from a Bluetooth device to the NAD, but also from the NAD to another Bluetooth device, such as headphones. If you prefer your headphones wired, there’s a dedicated output with 6.3mm jack on the front panel. Inside, the C 658 uses the popular ESS Sabre 32-bit DAC allowing sample rates of up to 32-bit/192 kHz in 16- to 24-bit resolution. Most file types are supported, including FLAC, WAV, AIFF, MP3 and AAC. DSD can apparently be played using the BluOS desktop app.

NAD uses the BluOS system for hi-res streaming. This is simple and intuitive, and the app (which is free for Android, PC, Mac and iOS) looks great and operates beautifully. It gives you most of – if not all – the top streaming services like Spotify, Tidal, Amazon Music, Qobuz, HD Tracks and Deezer. Your own hard drive-based music collection is also accessible, too. With BluOS, the C 658 can be used as a hub to stream HD music wirelessly to other BluOS-based products in other areas of your home, all controllable via smartphones, tablets and computers. Airplay 2 is also available for Apple users wanting similar functionality. For Tidal users, BluOS decodes and renders MQA (Master Quality Authenticated) streaming and files, enabling you to get the best out of an increasing number of MQA releases. A handful of online sites offer MQA files to purchase, for those who prefer to own rather than stream their music.

One fascinating feature is the inclusion of Dirac Live Room Correction, which tunes your loudspeakers to the frequency response of your room by running a frequency sweep and analysing the results via the supplied microphone, which is plugged into your computer. Measurements are taken at various points within the listening room with the option of utilising just a few or all of them, as you require. Once all the measurements have been recorded, a filter is created and sent to the C 658 which is accessed via the BluOS app. In order to begin this process, you need to download Dirac Live onto your computer, create an account and sign in. A limited frequency sweep is free, but you have to pay a one-off fee to access the full spectrum. Experience of this teaches me that it’s highly effective in many respects – and especially useful for people like me whose listening room is also the family living room, and where room treatments are not an option. It’s easy to use and gives users a satisfying sense of being involved in the process.

Measuring 435x100x405mm weighing in at 10kg, the full-sized C 658 is very well-built and finished. I know some people pull NAD up on their utilitarian looks, but in this case I rather like its purposeful, businesslike appearance. The large centred display is easy to read, and flanked by a handy rotary volume control and menu selector. A couple of source selection buttons, the power switch and headphone input round things off – it’s simple, uncluttered and easy to use. The comprehensive supplied remote control will keep couch potatoes happy, too.

Sound quality

The C 658 has a engagingly fluid sound which beguiles you from the moment you press play. The soundstage is wide with a fine sense of depth and cohesion, with the images clearly defined and well illuminated. I enjoyed the bouncy rhythmic flow and well-executed dynamics which together tended to encourage not just emotional but a physical interaction with the music. My reference laptop/DAC combo – MHDT Labs Stockholm, USBridge USB-S/PDIF convertor and AudioQuest JitterBug – sounded almost dull and unenthusiastic by comparison, as if I’d thrown a heavy blanket over my loudspeakers. The NAD is vibrant, punchy and crisp – all without sounding typically digital and totally devoid of listener fatigue. It does what the Bluesound Node 2i does well, only better, with more depth, holographic instruments, solid bass slam and overall clarity.

I don’t listen to The Beatles much, but since the 50th anniversary MQA mastered edition of ‘Abbey Road (Super Deluxe 2019 mix)’ came up in my Tidal Recommendations, I decided to give it a crack. On Come Together I was most impressed with the strength of the bass which thundered from my speakers, and the way each instrument was clearly defined and placed. The music had a vibrancy and freshness, making me think it could have been recorded five years ago, let alone fifty. I know some of the vinyl issues of this album, including from back in the day, aren’t thought of particularly favourably but this version is well worthwhile. Playing the same track, albeit without the fully unfolded MQA experience, through my PC reduced the excitement and rhythm and the bass level dropped significantly. The sound now lacked the thrilling dynamics and rhythmic drive and structure the NAD had provided. It was nice, but now I was aware of what I was missing.

Comparing both MQA mastered and standard CD-quality versions of Primus’s My Name Is Mud from their splendid ‘Pork Soda’ album, between the NAD and Stockholm, provided further proof of the C 658’s ability. While the sound with MQA and CD sounded bigger and bolder through the NAD, it was the drumming at the end which particularly caught my attention. When they were struck, not only was there more weight and depth but the resonance and decay of each strike seemed much more realistic. The MQA mix had more body and space, but both versions were highly listenable. For the most part, the NAD created a feeling of air and dimension around instruments. There was none of that sense of clutter where everything seems squeezed in and frigid.

Another highlight was Patrick Cowley’s Surfside Sex from the newly remastered ‘Afternooners’ collection in CD-quality 16/44.1k Hz. This is a jaunty, hedonic bit of electronica from the nineteen eighties which normally sounds very good, but the C 658 added a stronger bottom end foundation, upped the persistent rhythmic drive of the track and sharpened the edges of the notes and little effects. There was also an additional degree of spaciousness and depth, filling the room with sound.

Using the Dirac Live filter gave an already lovely listening experience a further fillip. It felt like there was more energy along with better spatiality; there was more room to hear the individual tonal qualities of each instrument. Opinion remains divided on room DSP, but this is well done and well worth exploring further in my view.

Relax cans fans, because there is no sense of the headphone stage being an afterthought. The same sense of space, dynamics and rhythmic appeal the C 658 dishes out through loudspeakers is there through headphones. I tried a range of over-ear models, IEMs and even my son’s astonishingly good gaming headphones, and in every case I was reluctant to take them off.

Overall then, the C 658 serves up a good solid bass end, alongside comparatively well balanced treble that’s never too forward or brash. In-between this, the midrange is elegantly rich and detailed without descending into dullness. It has a full and fleshy character – as opposed to being thin and weedy. There’s an organic sense to the way it makes music that’s hard not to like.

The Verdict

NAD’s C 658 shows just how far network music players have come in such a short space of time. Five or so years ago, something as good as this would have cost at least twice as much. As well as being packed with useful features, it has a seriously enjoyable sound that’s hard to beat at this price, or no small amount more. Well worth auditioning, if you’re serious about streaming.

For more information, visit NAD Electronics.