Review: NAD C 658 & NAD C 298 – No: NAD devices are usually not colourful, shiny and bling-bling. The rather inconspicuous is almost part of the NAD DNA, if this letter game is allowed. Even as a student, I had several of the always moderately priced integrated amplifiers in hard continuous use. Later I was allowed to test the C 390DD, also an integrated amplifier, and the NAD M32, a combination of streamer and integrated amplifier, for fairaudio. Now I immediately received a duo in the mail, consisting of the NAD C 658 streaming preamplifier and the NAD C 298 Class D stereo power amplifier (1,699 euros and 1,999 euros ) .
NAD C 298 power amplifier: Operation & technology
The external appearance of both amplifiers can be described with a clear conscience as “simple, typical of the company”. This applies in particular to the power amplifier, whose grey-black housing only has an on/off button on the front. It wakes the power amp from sleep, while the “hard” power switch is on the back. How much more is going on at the rear anyway: In addition to the speaker connections, which seem more pragmatic than over-the-top high-end, we find a stereo pair of XLR and cinch inputs as well as a control option for the input sensitivity in order to optimally adjust pending source devices or preamps.
It also has a switch on the back that can be used to determine the input voltage at which the NAD C 298 automatically wakes up from standby sleep based on three graded threshold values. A very practical solution, because in my experience such automatic switch-on functions often work somewhat arbitrarily with a fixed, non-selectable threshold value – this is definitely not the case with the NAD amp. Last but not least, the NAD C 298 can also be bridged to the mono output stage, instead of a continuous output power of 2 x 185 watts at 8 ohms, an impressive 620 watts at 8 ohms are then pushed out.
Up to this point, nothing about the power amp seems particularly exciting or innovative – it looks a bit different when you look under the hood. When developing the amplifier, according to NAD, efforts were made to exorcise the Class D technology used in a way that was not conducive to the sound: the so-called memory or hysteresis effect in the inductances of the output filters. For this purpose, a relatively young technology from the Danish manufacturer Purifi was licensed, which aims to prevent or compensate for this effect with a sophisticated circuit concept (if you are interested in the technical details, you can read an in-depth explanation of the technology at Purifi).
As a result, the NAD output stage is characterized by extremely low intermodulation distortion , a particularly low distortion factor and only minimal intrinsic noise. As further advantages of the Purifi technology, NAD praises the fact that the C-298 power amplifier reacts very insensitively to changing loudspeaker loads, as well as the high damping factor , which guarantees clean and controlled bass reproduction. That reads well on paper – we will find out later whether this is also the case in practice; but now a look at our player.
NAD C 658 preamp/streamer: interfaces, D/A conversion & Dirac room correction
In addition to streaming via Bluetooth and music services such as Tidal and Qobuz via LAN and WLAN , the NAD C 658 allows access to seven other sources – using phono RCA (MM), two high-level RCAs and four S/PDIFs (two coaxial and two optical). Mass storage drives can also be connected via the USB port, so that music can also be played from the USB stick or hard drive.
However, UPnP/DLNA is not supported. The good news: According to NAD, NAS storage should still be able to be used via the SMB (Samba Share) network protocol and integrated via the BluOS app – although I haven’t tried it out. Another special feature: on the left-hand side we find two plug-in slots on the back, with the help of which the preamp can be upgraded with modules and kept up to date – there is already an HDMI plug-in card, the three HDMI inputs and one HDMI output brings. NAD promises that further modules will follow. On the output side, the NAD C 658 comes up with two subwoofer connections as well as a cinch and XLR pair for the volume-controlled analog signal.
The DAC section was realized with an ESS Saber chipset, which can process material up to 24 bit/192 kHz. NAD’s own BluOS multi-room system is used as the streaming architecture. This can be used to control up to 64 different zones; BluOS is Apple Airplay 2-certified and Roon-ready and supports the well-known lossless audio formats ALAC, FLAC and WAV of everyday audiophile life as well as the MQA standard . The rendering of DSD data is not supported, however, in case that is of interest.
A special treat is certainly the Dirac Live room correction that can be used ex works, which actually provided a somewhat more contoured and drier/more precise bass reproduction for me (I’m getting ahead of myself). Of course, the extent of the resulting improvements depends very much on the listening environment: I am fortunate to have set up a separate listening room in our house, which eliminates some typical acoustic problem areas.
Thankfully, the NAD C 658 comes with a measurement microphone, with the help of which the Dirac room correction can be used immediately in a light version: All you have to do is download the Dirac Live app onto your smartphone and it will then guide you through the process. The particularly problematic frequencies up to 500 Hertz are analyzed using a sine sweep and a corresponding equalization curve is stored in the memory of the NAD-C-658 preamplifier as a preset (which can be switched off if desired). If you like, you can upgrade to the full version via the Dirac website for an additional charge of 99 dollars, which also “straightens out” the range above 500 Hertz. Oh yes: The analog inputs can either be operated as real analog branches via the configuration menu or looped via an A/D converter. The advantage: With the latter option, the analogue inputs also benefit – including the phono input! – from room correction.
The NAD C 658 is also visually rather reserved: I like the pragmatism of the controls: The really important functions (volume control and input selection) can be called up directly with pushbuttons or rotary controls, if you want to delve deeper into the numerous functions and fine adjustments of the device, it uses the operating ring to the left of the display, which is often found on NAD devices and consists of four “cursor keys” at positions 3, 6, 9 and 12 o’clock and a central “Enter” button.
Before I went to the sound check, I treated myself to a Dirac Light room correction, downloaded the BluOS app and stored the access data for my Tidal HiFi account there. Everything together took less than ten minutes – then I was ready to go.
First we listen to the NAD combo mediated via the digital section of the streaming amplifier, although I didn’t hear any difference worth mentioning between the high-resolution streaming via BluOS or the playback of an external digital source via coaxial S/PDIFs.
One thing is certain after just a few bars: the amplifier combination of NAD C 658 and C 298 offers liveliness and joy of playing par excellence. One of my favorite live recordings is the album Philip Catherine / Live, recorded at Nick Vollebregt’s Jazz Café in Laren, not far from Amsterdam. From my point of view, the most dazzling and multi-layered piece of this extremely good-humoured concert session, which was brilliantly recorded by the production managers, is the almost nine-minute long “I fall in love too easily”.
Initially, the Philip Catherine Quartet leads youmisleadingly – one thinks one is dealing with a slightly sleepy jazz ballad: leisurely tempo, the guitar not only seems a bit lame, the theme presented by it does not seem to be equipped with great compositional finesse. But far from it! When Catherine puts on the first solo/improvisation rounds after the introduction of the theme, the tension increases noticeably, because he comes around the corner with one or the other unexpected chord change, and his playing becomes increasingly virtuoso. At the same time, the keyboardist Bert van den Brink – initially still working in the background – sharpens his keyboard round after round: He has created a very unique sound, which in principle represents a simple 8-foot Hammond organ register, but consistently on vibrato, key click, percussion, Leslie and distortion are omitted – all electro-acoustic stylistic elements that Hammond organists like to use in excess. In doing so, he initially creates rather clean harmonies and sound surfaces, which are constantly getting louder and initially only underpin Catherine’s guitar playing harmoniously – before Catherine suddenly throws the baton over to him and at the same time the tempo of the song turns into an electrifying double-time: Suddenly it is Bert van den Brink the soloist, who plays a daring, part magmatic bubbling, part bitingly sharp solo while the drummer races in bebop fashion and the bassist holds off equally risky runs in the upper register. Whether what is heard comes across as “really cool” or whether it pulls you off the armchair with sheer joie de vivre and joy of playing – that is ultimately the question of the playback chain.
The duo of NAD C 658 and NAD C 298 is absolutely lightning fast (speed and agility spontaneously remind me of my Abacus Ampollo Dolifet power amplifier ) and manages to map the envelope curves of individual sound sources completely and precisely: from the first impulse (attack and transient) over the sustain to the release/decay/decay.
It doesn’t matter whether the fast bass runs flop into the room like small rubber bullets, whether the drummer’s edge hits against the beat give the already alert rhythm carpet a boost – or whether the organ shows bite and contours over its entire frequency range: The NAD -Amplifier combination leaves nothing to be desired. To put it absurdly: If you had this sound compete in the form of a race against a delicate 6-watt triode circuit, you could certainly think that the NADs had finished the piece a few seconds earlier. It is also worth mentioning that even the deep sixteenth notes on the organ still appear to be exactly comprehensible in their envelope and do not drown out in front of the bass player, who is poaching in the same frequency range. Totally on the ball, it’s endless fun!
Closely intertwined with good timing is the ability to map an enormous dynamic range and fire off decent performances from a standing start. When the drummer picks up the pace, intensifies the bass drum work and switches from brushes to sticks at the same time, the NAD team of C 658 & C 298 enthusiastically follows along. The bass drums kick, the cymbals hiss and boom – and when the piece finds its way back to its original tempo towards the end and Catherine fades the individual notes in and out with the volume pedal, no information is lost: At first you only hear the rather randomly captured sounds via the microphones , unamplified guitar strings, then the gradual fading in and out via the amp. Up to this point, the quality on offer is already above what can be expected for the price range;Bryston 3B3 power amp on .
On the tonal line, the combination convinces with neutrality and fun factor at the same time. While the NAD C 390DD was a bit milder than normal zero at the ends of the frequency response for my taste, the combination of NAD C 658 and NAD C 298 is then comparatively fresher in the high-frequency range and with a little more punch in the low-frequency range – and thus similar neutral like the M32 .
In my opinion, what is actually extraordinary can be felt in “Rumours” by the Kings Of Convenience (Album: Peace Or Love), where only two voices and two guitars strike up a dreamlike ballad. Although all the details are audible and the frequency response seems as smooth as if drawn with a ruler, one does not imagine oneself in a sterile hi-fi technology demonstration room when listening, but directly at a living room gig. Naturalness, authenticity, the feeling of being there: this also characterizes the space. If Nick Caveintones his piano ballad “Into My Arms” (Album: The Boatman’s Call, Remaster 2011), then with closed eyes it doesn’t take much imagination to imagine the melancholic Australian in the living room.
The voice stands in the room plastically and corporeally, the piano fans out broadly from left to right; the sound coach deliberately chose a slightly wider miking, so that the concert grand piano is illusory as being somewhat larger than is actually realistic. Nevertheless, the fanning out and the proportions seem coherent – just a little more expansive. When it comes to more complex arrangements – for example with Modest Mouses“Fire It Up” (Album: We were dead before the ship even sank), where a bellyy bass, several guitars, polyphonic vocals and oddly shimmering drum tones can be heard – the NAD combo proves to be a very exact usher with a precise Grid in width and depth. A grid that, by the way, sticks closely to the source material: If there is shoebox stereo (as with old Wipers records), then the team of NAD C 658 and NAD C 298 does not make a chamber music hall out of it.
Let’s take a look at the analog audio input of the NAD C 658. There is a case distinction here: If you select the “Analog Bypass” option, in which the entire signal processing takes place on the analog level, the preamp is similarly neutral as with digital control . No sound is “made” here, but passed through clearly and simply. It’s a little different if you send the analog signal through the A/D converter, for example to enjoy Dirac room correction. Basically, there is a similar character here – in terms of timing and dynamics as well as the type of stereophonic spatial presentation, the differences to the digital section are negligible. On the tonal side, on the other hand, there are minimal roundings or softening in the low bass and also in the treble range compared to the purely analog section, which obviously comes from the A/D conversion via the built-in TI-PCM-1863 chip. These roundings are rather subtle, but already audible when switching. If you take, for example, a track that comes along with plenty of synthetic sub-bass and razor-sharp, shimmering high-tone trap drum programming (“Hallelujah” byAudio 88 & Yassim ), it sounds a little more tame via the analog input with digitization than purely analog or streamed.
Last but not least, let’s take a look at the phono input again, which actually surprises me in terms of quality: the MM input of the NAD C 658 doesn’t have to hide compared to my Pro-Ject Phonobox DS+ (around 400 euros): in the low frequency range it’s a bit wiry and slimmer on the way, but again with excellent timing and a pleasing dynamic range. The highs are even a bit better resolved and a bit more powerful than with my phono box, which favors a more velvety tonal gait. It goes without saying that a proper, full-fledged phono preamplifier can do more, especially in the stereophonic depth gradation of the delicate MM signals – but what is offered is more than okay for an integrated solution.
NAD C 658 and NAD C 298: comparisons
Would you like a few more cross-comparisons? In a direct comparison to the Hifi Akademie Stream6-mini , which is available to me as a work tool (and is priced considerably lower at 795 euros), the NAD-C-658 streamer is ahead of the game, especially in terms of coarse dynamics and fine resolution in the mid and high frequency bands. Not to mention extra features like Dirac calibration. The Lindemann music book SOURCE , on the other hand, has surprisingly similar characteristics to the sound of the NAD C 658(3,280 euros). With the latter, I also liked the amalgamation of neutrality and pleasant ease, combined with excellent fine and coarse dynamic abilities. With the chic Lindemann, however, you get a device that appears to be more valuable, not least in terms of the use of materials and processing quality.
Last but not least, let’s take a look at the NAD C 298 power amplifier in isolation. It’s not even half as expensive as my Abacus Ampollo Dolifet and has almost the same performance data. And sonically? Well, the two optically rather dissimilar opponents are amazingly similar: Accuracy, fine resolution, dynamics: It could almost be a neck-and-neck race. The Abacus power amplifier also offers a bit more depth and draft on the bass side and illuminates the treble a notch more precisely (perhaps a little fresher than normal zero). Otherwise, it scores with a handy level control that makes a preamp unnecessary for purists – and again with an overall more valuable appearance and processing quality. Otherwise, however, the NAD power amplifier is an amazingly dangerous opponent for the Abacus power amplifier,
Conclusion – NAD C 658 & NAD C 298
Both the NAD streamer/preamplifier and the NAD power amplifier are alert and nimble, powerful and agile on the move, which conveys a good deal of gripping listening fun, with an exemplary neutral and beautifully detailed presentation at the same time. The NADs are therefore less aimed at listeners who prefer romantic sounds or sounds with an emphasis on melting.
On the plus side, there is also the wealth of features (room measurement, Roon-Ready, Apple AirPlay2, multi-room with 64 zones, phono) and the BluOS ecosystem that runs extraordinarily stably in everyday life. If you don’t care that the amps aren’t exactly good to show off visually, you can let the NADs tear you off your stool for a not small, but absolutely justified thaler in terms of sound.
Profile NAD C 658 & NAD C 298:
- Smooth, clean frequency plot, as if drawn with a spirit level, but not analytically pale, but colorful and with a grain of analogue appeal.
- Solid bass foundation, albeit with a slight focus on agility rather than maximum low-end frequency. Especially in the power amp area, there are still devices that descend deeper into the bass cellar and bring a little more stability in the lowest octave. Still more than enough for most classic stereo applications.
- Well connected to the low and high frequency range, transparent mid-range reproduction with a subtle pinch of warmth.
- Fresh, clear, tidy treble, which – with the appropriate music playback – can also get a grip, but at all times refrains from insubordinate harshness or hissing.
- The analog inputs are an iota milder at the frequency response ends, unless the analog bypass is selected.
- Great dynamics: Large reserves of power can be mobilized from a standing start, but the fine definition of quiet details is also well above the price range. The combo comes with a turn-on factor that brings enormous listening pleasure without being annoying or stressful.
- The stage set-up is primarily based on the source material. From “narrow” to “ultra wide” everything is possible, the NAD combination is not a bottleneck here. Precise, drawing board-like rather than “hugging” positioning and localization of sound sources.
Facts NAD C658
- Category: Streaming Preamp / DAC
- Price: 1,699 euros
- Inputs: Phono MM, line level (2x), USB (mass storage), S/PDIF Toslink (2x) and coaxial (2x)
- Streaming via LAN, WLAN and Bluetooth (aptX), not UPnP/DLNA compatible
- Supported streaming services: Spotify, Amazon Music, Tidal, Deezer, Qobuz, HDTracks, Napster, HighResAudio, Murfie, JUKE, Slacker Radio, KKBox, Bugs
- Outputs: Cinch and XLR volume controlled, subwoofer (2x)
- Data rates: 24-bit/192kHz
- Dimensions (WxHxD) & weight: 43.5 x 10 x 40.5 | 10.1kg
- Colour: dark grey
- Warranty: 2 years or 5 years upon product registration
Facts NAD C298
- Category: Class D stereo power amplifier
- Price: 1,999 euros
- Inputs: RCA / XLR
- Continuous output power at 8 ohms: 2 x 185 watts / 1x 620 watts bridged
- Dimensions (WxHxD) & weight: 43.5 x 12 x 39 cm | 11.2kg
- Colour: dark grey
- Warranty: 2 years or 5 years upon product registration