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 like yours truly. MQA CD, however, and I tried several of them, are not recognized by the C658.
As a sound calibrator with music production background, the most fascinating feature is the Dirac Live Room Correction. 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 and calculated, a filter is created and sent to the C658 which is accessed via the BluOS app. You need to download Dirac Live onto your computer, create an account and sign in. Too bad while limited frequency sweep is free, you still have to pay a one-off fee to access the full spectrum version. To me this is highly unacceptable. Who in the right mind will only use the limited frequency sweep ? NAD should have provided the full spectrum sweep included in the price of the C658 or don’t have it all. There is nothing worse than right after you paid for equipment and you need to pay AGAIN just to use the advertised feature properly.
I listen to a LOT of The Beatles, my early music collection started with cassette recordings of nursery rhymes AND The Beatles. I used to own the complete Beatles albums on cassettes, vinyl, CDs which have now been upgraded to both remastered vinyl and remastered CDs. 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 thundered from my System Audio Aura 30 speakers coupled with PSB SubSeries 450 subwoofer. Regardless of which track I played, the music had vibrancy and freshness, giving me the illusion that they could have been recorded yesterday, not 50 years ago. This is post Dirac Live full spectrum calibration, of course. I wouldn’t listen to the system any other way. Opinion remains divided on room DSP, but this is well done and well worth exploring further. To me it’s very simple; if recording studios worldwide have embraced the use of DSP in order to create music, how smug do we have to be in not embracing the same technology in our humble abode?
Overall then, the C658 serves up a truly solid low end together with a well-balanced high end that is clear but never too brash. The midrange is warm but not overly so without any hint of dullness in the week long period I listened to this unit be it from vinyl or streamed from the Internet and hard-disk drive.
While I still don’t buy into streaming just like I never bought into radio even since I was a wee lad, NAD C658 shows just how far network music players have come. Just several years ago, in order to get a pre-amp/DAC/streamer/whole-home audio in a single box would have cost beyond $5,000 CAD. The only drawback is the Dirac Live. It should’ve come with the license for a full-spectrum version instead of the not-useful limited sweep (light) version. Regardless of my stance in streaming, this unit is highly recommended.