NAD C 510 Direct Digital Preamp DAC
Input: AES/EBU XLR, 1x SPDIF Coaxial, 1x Optical, 2x HDMI (2-channel PCM), USB Class 2 Audio: asynchronous 24/192 support, IR In, Trigger In 12V ±20%
Output: HDMI Video Out (3D video pass through), Analogue Unbalanced RCA, Balanced XLR, Trigger Out 12V ±20%
Dimensions: 435 x 99 x 309mm (17 1/8 x 3 15/16 x 12 3/16 inches)
Weight: 4.7kg (10.4lb)
Availability: Online and Authorized Dealers
Direct Digital Trickles Down (and Up)
NAD's C 510 inherits its impressive innards from the company's M2 Direct Digital Amp (see Stereophile's review) and M51 DAC (see Stereophile's review). All incoming digital data (up to 24/192 PCM), the C 510 does not offer any analog inputs, is converted to a pulse-width-modulation (PWM) signal at a sampling rate of 844kHz before being converted to analog. Volume control is also handled in the digital domain and the C 510's 35-bit architecture allows for transparency at any level, in theory. Here's more from NAD, "Due to the very high clock speed [108MHz] and mathematical precision of our reconstruction filters, the resulting audio signal is totally free of digital artifacts like ringing." I suppose the only question remaining is—does all this work to make digital sound less...digital?
Beyond the usual asynchronous USB, Toslink and Coax inputs, the C 510 adds AES/EBU and two HDMI inputs for 2-channel PCM data. Outputs offered include single-ended RCAs and balanced XLRs driven by a Class A-biased operational amplifier (Burr-Brown OPA 2134). Since the C 510 supports up to 24/192 data via USB, Windows users have to download and instal the NAD drivers from the company's website to take full advantage. MAC users can skip this step. There's also a USB Type-A input for firmware upgrades, RS232 for connecting to AMX and Crestron devices, as well as +12V Trigger In/Out for controlling external like-equipped devices. Finishing things off around back are the power switch and IEC inlet for the included power cord.
The C 510's front panel is rather spartan and workman-like in that NAD Army/Navy way. There's a Standby button, a roughly 6.25" vacuum fluorescent display which shows the incoming sample rate of the file being played, selected input, and volume level, source selector buttons, and the volume control knob. NAD also includes a multi-function remote duplicating the front face functions while adding the ability to dim the display. You can also control other NAD gear with the same remote.
The C 510's USB input was fed its bits from my MacBook Pro's output (running Roon software) and on the other end the 510's XLR output connected to my Pass INT-30A. I used the C 510 to control volume.
The NAD C 510 sounds like a very refined DAC. It also sounds uncolored, precise, and in control. I used the NAD's volume control for the duration of this review and found it be, for all intents and purposes, transparent. All told, I dare say the C 510 also sounds like more than its $1299 asking price.
The space of the recording is reproduced with clinical precision and what strikes me as a somewhat less dimensional sound image as compared to the more expensive Auralic Vega DAC I use as my reference. The Vega is more lush while also throwing out a larger sound image in every dimension where the C 510 creates a a more condensed and somewhat shallower sound space. I'd imagine some listeners could interpret this difference differently, describing the NAD as being truer to the recording but that's not how I hear it. My preference falls toward the Vega in this regard albeit at more than twice the NAD's price.
I mostly listened to the NAD using my MacBook Pro over the course of 4+ weeks but I also spent a few days trying out the C 510's AES input using the review sample Bel Canto REFstream network player. I'll obviously be talking more about the latter later but I will say that the NAD appreciates what strikes me as a less noisy signal. There was an even greater sense of clarity and precision with the Bel Canto that allows you to hear further into the recording. Like most DACs that appear uncolored, this also means that crappy recordings tend to sound crappy through the C 510.
Bass response is very well controlled and in no way bloated, there's a restrained richness in tone color not at the same lushness level as the Vega DAC, and upper registers sound convincingly crisp without unnatural bite. This thing sings, especially when the source material has been well cared for. I found myself looking for recordings that present a natural sense of space coupled with good sound. Ravel's "La Vallee des cloches" as interpreted by Percy Grainger from In A Nutshell (CD rip) was particular lovely as was Ella and Louis joisting on "Isn't It A Lovely Day" from Ella & Louis (24/96). Some of my favorite songs, like Nick Cave's "Love Letter" from No More Shall We Part (CD rip) was perfectly clean and precise but I felt there was some emotion lacking which I'd interpret as a slightly dry presentation.
I'd like to point out that mentioning specific albums and songs is potentially misleading since I spend many weeks listening to review components so specific music mentioned is to highlight standout qualities. They are by no means a complete list of recordings used for the review since that number gets into the dozens of albums. When I see a list of recordings used for a review and it contains a handful of albums, I wonder how someone can get beyond ticking off a few sonic points without missing the bigger and more important picture of what it's like to live with and listen through a given component as if you own it.
The Mytek Stereo192-DSD DAC, which I use every day in my desktop system, offered a more appropriate comparison price-wise as it comes in at $1495. On a spec-sheet basis, the Mytek adds DSD playback, a Firewire input, filter options, analog and digital volume controls, and two headphone outputs. In terms of music, my tastes have me preferring the Mytek's weightier and wetter sound. Ella & Louis have more physical presence, Nick Cave's vocals convey his emotional shifts more convincingly, and Tom Waits sounds more guttural. While the Mytek's overall presentation is slightly softer and less well defined as compared to the NAD, I'm willing to make this trade off.
Another way to say nearly the same thing is I find the NAD C 510 to appeal more to my intellect than to my emotions. Ultimately the choice of the NAD versus the Mytek or any other DAC will come down to personal preference and system matching. Whether one DAC is "better" than the other doesn't enter the reality equation.
Direct Digital Indeed
Listening to and living with the NAD proved to be musically satisfying and the few shortcomings I heard mainly dissolved over time. Of greater importance than what the C 510 does not do is what it does so well namely delivering a very clear and precise presentation of the music captured in the recording while doing double duty as a very capable digital preamp. For many listeners, you really can't ask for much more.
Also in-use during the NAD C 510 review: Mytek Stereo192-DSD DAC, Auralic Vega