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The Ultimate HiFi Hub | NAD Masters M66 Complete Analog/Digital Preamplifier

March 13, 2024



The NAD Masters M66 is a highly advanced preamplifier, designed to be the literal “Brain” of a modern HiFi system. With seemingly endless capability on both the analog and digital fronts there isn’t much it can’t do. The only thing would be amplification, but that’s for someone seeking a true all-in-one solution like a fully integrated amplifier with built-in streaming and phono stage. If you are looking for separates sound quality, but don’t want to completely separate everything out—separate streamer, separate phono stage, DAC, etc—then the M66 is for you. Oh, and it does room correction as well—we weren’t kidding about endless capability. 

NAD M66 Design and Chassis

The M66 offers a sophisticated, well-built chassis with a singular control knob and “star of the show”—a 7” touchscreen to elegantly display all the functions and album artwork. It pairs perfectly with NAD’s Masters M23 power amplifier, but can be paired with other power amps if you choose.  

NAD M66 Streaming Capability

As with most things regarding the M66, streaming capability isn’t in short supply. It gives you access to more than 20 high-res (up to 24-bit/192kHz) streaming services via the BluOS app and has Tidal Connect, Spotify Connect, and Apple Airplay 2. Furthermore, the M66 can control playback by voice using Alexa or Siri and it integrates with home automations systems from Control4, Crestron, and more. 

However, the real digital fireworks are with its BluOS multi-room capability. The M66 can integrate with a BlueSound ecosystem and play music in any room whether through a Bluesound wireless speaker or any other device with BlueOS on board. It can even transport analog from the phono stage to digital, so you can run a turntable through the M66 and play your records in multiple zones. No longer analog, but who won’t want the opportunity to play  records anywhere in the house. 

NAD M66 Room Correction Capability

Few rooms sound perfect. And if you can’t dive into acoustic treatment for various reasons—it might not jive with your decor for one—room corrections systems are a good way to go. The M66 has Dirac Live Room Correction built-in. Just connect with your smart device and the app walks you through the calibration, resulting in much better sound, even in the most acoustically challenged rooms. 

There is even Dirac Live Bass Control that is built-in to the M66. This allows you to get the most out of the four balanced and unbalanced subwoofer outputs—a first for a stereo component. That’s right you can hook up four subs, and using the Dirac Live Bass Control, place them strategically throughout the room to blend perfectly with your main speakers and achieve a full range of sound only possible by high-dollar mega systems. 

NAD M66 Digital Section

The M66 features an ESS Sabre ES9038PRO DAC to convert digital to analog as well as a ES9822PRO ADC chip for when you want to use the Dirac Room Correction system on your records—converting analog to digital. Driving the conversions is NAD’s Dynamic Digital Headroom circuitry. This unique technology helps eliminate the sharp highs that are common with digital sources, resulting in a smoother sonic presentation. 

NAD M66 Analog Section

As mentioned, the M66 will allow you to convert the built-in MM and MC phono stage to digital so you can use Dirac Room Correction or do multi-room. But for a pure analog experience, the M66 features Analog Direct mode, bypassing all digital processing, which means you can use the completely separate and shielded analog section with discrete power supply to its fullest. Any digital interference is removed, giving you the ideal analog sound—smooth, lush, and textured. 

NAD M66 Inputs & Outputs

From analog to digital there are a complete suite of inputs on the M66. Starting with analog, in addition to both of the aforementioned MM and MC phono inputs, there are both line-level analog inputs and balanced inputs to handle external analog sources like a CD player or streaming DAC. On the digital front, there are two coaxial and two optical inputs, as well as AES/EBU balanced inputs. And for video, an HDMI eARC port to integrate seamlessly with your TV and remote. There is also an ethernet connection for direct streaming, WiFi to go wireless, and a USB input for stored digital files from a thumb drive, server, or computer. 

The M66 is also well appointed when it comes to outputs. You can connect to an external power amplifier via both unbalanced RCA and balanced XLR. And as mentioned previously, there are four subwoofer outputs–both balanced and unbalanced. 

NAD M66 Sound Quality and Final Thoughts

It’s just mind boggling when you think about the capability of the M66. To call it a preamp doesn’t do it justice. It really is the “Brain” of a modern Hi-Fi system, offering “do-everything” functionality without cutting corners on sound, which isn’t traditionally the case with components like this.  Given its separate, isolated analog and digital sections with discrete power supplies, complete balanced inputs and outputs, DA and AD converters, and Dirac Live Room Correction, the M66 sounds like a fully fleshed out reference system built from separates in every category. The sonic presentation is detailed and precise but lacking in harness—refined to say the least. All told, the M66 could very well represent a milestone in audio history—the first all encompassing HiFi Hub that achieves the reference-level performance of a multitude of components—capability and sound quality all-in-one.