NAD C658 and C298, In Search of the Lost Sound

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High-fidelity is an obsession game. Like Indiana Jones chasing the Lost Ark, we’re always on the hunt for the perfect sound. But the reality is simpler: it doesn’t exist. What sounds like a revelation today might seem insufficient tomorrow. And when we finally find something close to perfection, we realize it costs as much as a luxury car.

The NAD C658 and C298 system isn’t a fetish for collectors. It doesn’t aim to be untouchable or placed on a pedestal. It’s, in fact, a system that promises power, precision, and neutrality, without embellishments or artifices. But does this approach manage to stir emotions?

To find out, I built a system with the Polk R600 and the SilentPower LAN iPurifier Pro, activating the DIRAC Live included software in the C658 to try to address an issue.

NAD C658, The Control Center

The NAD C658 is not content to be just a DAC. It’s a real operation center. It’s a streamer, a full preamplifier, an acoustic correction processor, and can be the central piece of any modern hi-fi system:

BluOS – Multiroom streaming with integration options for Roon, Tidal, Qobuz, Spotify, AirPlay, and online radio.
ESS Sabre 32-bit DAC with MQA support.
Preamplifier with analog, digital, and MM phono inputs.
Dedicated subwoofer outputs with configurable crossover.
Integrated DIRAC Live acoustic correction.
Bidirectional aptX HD Bluetooth (sends and receives wireless audio).

The C658 offers all of this for €2,000.
A point to improve? It doesn’t support native DSD, but let’s be honest: how many DSD files do you actually have? Exactly. And if you do, the C658 converts them to PCM.

What did I connect to the C658?

My reference turntable, during the stay of the NAD system for review, was the MoFi StudioDeck. But there was also a strong contender for this throne: the Avid Ingenium.

NAD C658 + C298 + MoFi Studiodeck + Rothwell Simplex + SilentPower Lan iPurifier Pro

I also tested the line inputs with the Volumio Primo and the Exposure XM HP.

Digital was handled by BluOS and Airplay (to compare Tidal, Qobuz, and Apple Music), as well as my Highsense TV (now I’ve really hit rock bottom) to listen to music via Apple Music with album artwork and lyrics on a 58-inch screen.

Bidirectional Bluetooth (approved by my eldest daughter and her wireless headphones).

The integrated MM phono stage is decent, but it doesn’t match the resolution and musicality of dedicated amplifiers like the Rothwell Simplex or Avid Pellar I had at hand. For those who aren’t obsessed with vinyl, it does the job.

The headphone amplifier, tested with the Meze 99 Classics, proved solid and musical but lacked the sophistication of dedicated amplifiers like the McIntosh MHA200 or Exposure XM HP, with which I compared it.

The NAD C298 – Power with Control

If the C658 is the brain of the system, the C298 is the muscle and the alpha male of the pair. Featuring Purifi Audio’s Eigentakt technology, this Class D power amplifier promises zero audible distortion, absolute bass control, and a fast, precise response. It promised. And it delivered!

Main Specifications:

185W per channel at 8 ohms and 340W at 4 ohms.
Mono mode in Bridge: 1000W at 8 ohms!
Balanced XLR and RCA inputs. Tested with AudioQuest XLR cables.
Line output for additional amplifiers.

What did this mean?

An extremely clean, dynamic sound with no harshness, even at high volumes.

🎵 “To France” – Mike Oldfield
Organic, textured mids, with extended and smooth highs – something that doesn’t always happen on Oldfield’s records.

🎵 “Forbidden Colours” – David Sylvian & Ryuichi Sakamoto
A decisive attack on the kick drum. Sylvian’s voice gains an intimate, golden tone, while Sakamoto surrounds it in an ethereal landscape.

The first auditions were with the Triangle Borea 03 and Bowers & Wilkins 607 S3.

First conclusion? The C298 isn’t afraid of dynamics and impact. Now, I needed to see how it handled more demanding, higher-performing speakers.

The First Impact with the Polk R600

Now, it was time for a real challenge. The Polk R600 came into play – dynamic, expressive, and with powerful bass. Maybe too much for my room, which is under 25m².

The initial combination with the NADs was impressive:

Deep bass.
Wide soundstage, without clipping at high volumes.
Well-defined instrumental separation.

🎵 Dvorak “9th Symphony” – Ohio Northwest Region Orchestra
The drama is all there, the cymbals shine but don’t overshadow the rest of the orchestra.

🎵 Beethoven’s “7th Symphony Allegretto” – Vienna Philharmonic & Carlos Kleiber
The strings have body and scale, but the bass was dominating the room.

The results were stunning, but there was a problem: the bass was taking over the room. That’s when DIRAC Live came into action.

DIRAC Live – Savior or Censor?

DIRAC Live, included in the C658 (a microphone comes included), measures the room response and applies filters to smooth resonances and improve sound coherence.

🎵 Tchaikovsky “Piano Concerto No. 1” – Van Cliburn & Kirill Kondrashin
Impeccable attack and timbral richness, but some bass impact was lost.

🎵 Delibes “Lakmé’s Flower Duet” – Natalie Dessay & Delphine Haidan
Crystal-clear, captivating female voices.

What improved?

More articulated and less invasive bass.
Clearer mids and highs.
More cohesive soundstage.

What was lost?

The music became more polished than it should have been.
The mids lost texture.
Less impact in the bass.

DIRAC solves room issues, but it can “pasteurize” the sound. Is it worth it? That depends on your taste.
Solution? One is choosing the right speakers for each space.

The Arrival of the SilentPower LAN iPurifier Pro – The Revelation

Then came the LAN iPurifier Pro – and everything changed.

The NAD system was already precise, controlled, and three-dimensional, but now, yes! A little more air between the instruments, and the instruments perfectly cut on the soundstage.

The impact was immediate.

The voice gained a holographic focus in the center of the soundstage.
The bass became more solid, with more texture.
Each instrument seemed suspended in its own three-dimensional space.

🎵 Orff’s “Carmina Burana“, performed by the New Philharmonia Chorus & Rafael de Burgos, and Leoncavallo “Vesti la Giubba“, sung by Plácido Domingo with the London Symphony Orchestra conducted by Nello Santi
Now, yes! A three-dimensional soundstage, with space between instruments and Domingo’s voice commanding the center.

Classical music, the ultimate test:

The strings revealed in distinct layers, instead of blending into one block.
The choirs shone with more brilliance and texture.
The percussion had a realistic impact, without interference from neighboring frequencies.

🎵 “Half Day Closing” – Portishead & “Pilots” – Goldfrapp
The extreme detail reveals everything – even less successful recordings.

After hearing this system with the SilentPower LAN iPurifier Pro, I don’t want to go back. Without it, the sound is still great – but with it, everything becomes more vivid, more cut, more real. This little surprise box isn’t going anywhere!

NAD C658 and C298. Is It Worth It?

The search for the perfect sound is, in the end, an exercise in balance. The NAD C658 and C298 bring precision, power, and absolute neutrality – essential qualities for anyone who wants to hear the music without any masks. Indiana Jones, the explorer who chased the whereabouts of the Lost Ark, discovered traps along the way.

DIRAC proved to be a powerful tool for refining the sound, but in the process, it ended up filtering it. Like any filter, it can clarify or remove part of the essence, depending on how it’s used. The key, for me? Choosing the right speakers for the space.

If you seek precision, transparency, and effortless power, this system is bullseye.
DIRAC can be a valuable tool – but it doesn’t work miracles.
The SilentPower LAN iPurifier Pro is a mandatory upgrade for those who want to extract the maximum three-dimensionality. Warning: improvements can be striking or practically nonexistent, depending on the upstream network player (see the Volumio Rivo review).

In the end, the NAD C658 and C298 system doesn’t invent anything – it just delivers the music as it was recorded. If you’re looking for coloration and sweetness, you’ll have to look elsewhere. If you want dynamic, decided, true sound, this could be your Holy Grail.