NAD C658 Streaming DAC Review

[Dathzo]

I'm about to buy one of these unit from the second hand market.
However, I keep reading these horrible reviews about popping sounds from the subwoofer, low subwoofer output. All kinds of different problems. Most of these reviews are from 2021 or before.
Have NAD fixed these known issues through firmware updates or is this unit still a no-go?

I'd love to get some input. Thanks !

It’s a great unit. I had it for 3 years and enjoyed it much. On the positive side:

1. Easy to use, inputs are detected automatically from a signal
2. Tons of features, you can connect all your gear
3. Pretty decent sound quality
4. Firmware keeps updating and you may even see DLBC soon

On the negative side of things (for some people):

1. Some Sub models suffer from low level depending on their sensitivity. I used SVS SB-1000 pro without problems (lower levels than other systems, but still usable). However, when subwoofer(s) (either 1 or 2) are enabled, the unit will produce clipping distortion on some tracks that are recorded “hot”. This was the thing that was annoying me the most
2. Any Dirac correction applied will affect all the outputs, including the headphone amplifier. It is very easy to turn it off. You can eventually have a unique profile for headphones with Dirac, but I’m not sure how easy it would be to do those measurements/correction. The headphone amplifier is not great BTW
3. SINAD is not great, although as said above, it does not affect the sound quality
4. Yes, there are some clicks here and there (mainly when changing tracks at different sample rates) that may bother some. The system never suffered from any pops

Just ask if you need further info

 

[JoetheLion]

I also had one for a few years and never had a problem. The only disadvantage I found was the largely useless headphone output (no individual volume setting, Dirac has to be switched off manually every time). Otherwise very reliable and faultless.

 

[terfenol-D]

@JDRCapeCod @JoetheLion - why did you both end up getting rid of it? What did you replace it with? I’m really asking if there’s something new I should be looking. So far I am not aware of anything that does everything the c658 does.

You can count me as someone who is more or less happy with mine.

 

[Reed]

I’ve had my C658 for about three years. No issues with Dirac or sub output. My biggest complaint is with how BlueOS handles AirPlay. Volume can be very loud if switching from another source - like Tidal Connect. There is now a volume range control in the app but I think it’s global and not just for AirPlay. I wanted a preamp that offered Dirac and balanced output for my Genelec monitors and it does that perfectly. The only cost effective alternative is a Mini DSP Flex, AFAIK.

 

[JoetheLion]

@JDRCapeCod @JoetheLion - why did you both end up getting rid of it? What did you replace it with? I’m really asking if there’s something new I should be looking. So far I am not aware of anything that does everything the c658 does.

You can count me as someone who is more or less happy with mine.

I have replaced my C 658 and C 298 with an M10. Costs less, is more compact, has a nice display, no difference in sound.

 

[LuvTheMusic]

Same here: I had mine for a couple of years, sold it to a good friend who has been using it with no issues ever since. The only reason for change was substituting a specialized processor that duplicated most of the 658 functions; otherwise I would still have it.

 

[JDRCapeCod]

@JDRCapeCod @JoetheLion - why did you both end up getting rid of it? What did you replace it with? I’m really asking if there’s something new I should be looking. So far I am not aware of anything that does everything the c658 does.

You can count me as someone who is more or less happy with mine.

I ended up replacing mine with an NAD M33. I feel the C658 is a better device since the phono stage on my M33 is digital and doesn't have enough gain when using Dirac.

 

[Dexter_prog]

Hi there. I am considering buying this one for the sole purpose of using Dirac (and as a digital source). I was wondering if I could get some perspectives on how well or not Dirac works as a room correction software. I know minidsp has some cheaper (and not) alternatives, but I found a couple of used C658 that are better pricewise

 

[terfenol-D]

Hi there. I am considering buying this one for the sole purpose of using Dirac (and as a digital source). I was wondering if I could get some perspectives on how well or not Dirac works as a room correction software. I know minidsp has some cheaper (and not) alternatives, but I found a couple of used C658 that are better pricewise

Dirac works great.

 

[bluefuzz]

I was wondering if I could get some perspectives on how well or not Dirac works as a room correction software.

Life changing.

Also the C658 has four channels of Dirac (two mains and two subs) whereas all MiniDSPs implementations have only two channels.

 

[SIY]

Hi there. I am considering buying this one for the sole purpose of using Dirac (and as a digital source). I was wondering if I could get some perspectives on how well or not Dirac works as a room correction software. I know minidsp has some cheaper (and not) alternatives, but I found a couple of used C658 that are better pricewise

Of the four or five correction schemes I've used so far, it has been the best by a large margin.

I have two others on the way, we'll see if it remains champion, but either way, it is a superb system IF you are careful with the measurements and correction targets.

 

[terfenol-D]

Life changing.

Also the C658 has four channels of Dirac (two mains and two subs) whereas all MiniDSPs implementations have only two channels.

I thought minidsp Dirac could handle two mains and two subs.

 

[LuvTheMusic]

I'm no expert, but my guess is that Dirac is Dirac, within whatever limits are imposed by the hardware. That is, the algorithm(s) that Dirac uses are the same. What I don't know if whether the functionality is limited by the hardware processor in particular units, but it would be surprising if the miniDSP was all that much different in this respect.

BTW, the default version of Dirac on the 658 is Dirac Lite, meaning it corrects only up to 500 Hz; you can upgrade that to full range but a lot of people say it's not worth the bother.

 

[Jaxjax]

I use the c658 & have full Dirac. It is well worth it & the c658 on its own is awesome. 4 years on mine. Full was worth it for me because there is always something above 500hz that I want to cut mildly for my taste.

 

[Sparkles]

I thought minidsp Dirac could handle two mains and two subs.

I use Minidsp Flex. Yes, it has 4 outputs. Dirac for Flex however treats all outputs as one set of L and R stereo measurement (with the algorithm options for listening position coverage). I recall that C658 stores 5 Dirac playback settings while Minidsp stores 4. Minidsp also runs Dirac on top of manual speaker dsp, so you have more tuning options.

Having experience of both, the results of Dirac are equally impressive in sound stage improvement. Speakers really do disappear.

I replaced C658 to chase DAC resolution and opportunity to try DSD, but in all honesty, the C658 provides enough and is a great integrated solution.

 

[bluefuzz]

I thought minidsp Dirac could handle two mains and two subs.

This is the signal flow of the MiniDSP Flex:

Only two channels of Dirac so sub and mains would be treated as one speaker for Dirac purposes whereas on the C658 they can be adjusted separately. Whether that makes a big difference in the end is another matter and the C658 doesn't have any manual PEQ capabilities of course.

 

[pogo]

I replaced C658 to chase DAC resolution and opportunity to try DSD, but in all honesty, the C658 provides enough and is a great integrated solution.

There is no point in replacing the DAC if miniDSP only works with max. 48/96kHz. NAD works up to 192kHz (DL processing). DSD must first be converted to PCM for DL. The C658 can be equipped with an optional module for this purpose.
PEQ is also possible with headphones on the C658, for example.

 

[Dathzo]

I have owned both the C658 and the minidsp SHD. They both will do a great job with Dirac. I preferred the NAD as it was more versatile with its inputs and easiness to use (BluOS). If you find something that is price attractive, I would say go for it. One thing: with Dirac Live, it will correct the subs and speakers separately, but their integration is not going to be great. For that you would need DLBC. Small chance it will come to the C658 at some point in time. No chance it will come to the SHD due to the way the channels are routed

 

[Sparkles]

There is no point in replacing the DAC if miniDSP only works with max. 48/96kHz. NAD works up to 192kHz (DL processing). DSD must first be converted to PCM for DL. The C658 can be equipped with an optional module for this purpose.
PEQ is also possible with headphones on the C658, for example.

Yes, agreed. I use the Minidsp as the DAC. No extra DAC. I did try inserting a newer DAC -> XLR -> Minidsp analog input, but the result was not better. Shoot me for being curious.

Interested in which addon module? How do you PEQ headphones on C658? Do you mean something in BluOs? I use the Bluesound Node as my streamer.

 

[Sparkles]

There is no point in replacing the DAC if miniDSP only works with max. 48/96kHz. NAD works up to 192kHz (DL processing). DSD must first be converted to PCM for DL. The C658 can be equipped with an optional module for this purpose.
PEQ is also possible with headphones on the C658, for example.

Are you sure DL on C658 runs at 192khz?