NAD C658 Streaming DAC Review

[Dathzo]

Maybe a question to the broader community. NAD C658 or miniDSP SHD? And why? I posted the same question on the SHD thread, but it is also fair to do it in this one as minidsp owners may be biased.
Thank you for your thoughts

 

[bluefuzz]

minidsp owners may be biased

As may C658 owners - of which I am one ... ;-)

I'd say, if you need PEQ filters for implementing a crossover, for example, then the SHD is obviously the one to go for as the C658 can't do that. Otherwise I'd go for the C658. It has a more flexible Dirac implementation, and BluOS is vastly preferable to Volumio (IMHO). The C658 is bizarrely lacking a USB input so if that is important then, again, the SHD wins. However the C658 has two each of the other inputs which can be useful. Ultimate SINAD measurements are better on the SHD, but in the real world it's unlikely anyone could hear the difference.

Both devices have various reported bugs that affect some users. I have never experienced any problems with my C658.

 

[Dathzo]

As may C658 owners - of which I am one ... ;-)

I'd say, if you need PEQ filters for implementing a crossover, for example, then the SHD is obviously the one to go for as the C658 can't do that. Otherwise I'd go for the C658. It has a more flexible Dirac implementation, and BluOS is vastly preferable to Volumio (IMHO). The C658 is bizarrely lacking a USB input so if that is important then, again, the SHD wins. However the C658 has two each of the other inputs which can be useful. Ultimate SINAD measurements are better on the SHD, but in the real world it's unlikely anyone could hear the difference.

Both devices have various reported bugs that affect some users. I have never experienced any problems with my C658.

That’s exactly what I’m looking for: the bias from the C658 owners on this one . Thanks for your input. Fully agree that bluOS is far ahead compared to buggy Volumio. I don’t care about usb input as I would be streaming music, most likely using Roon. And then, SINAD of 90 may be an engineering problem, but I doubt it’s audible. So far so good with the NAD device.
Finally, PEq is nice to have, but I am assuming Dirac would do its job and this becomes redundant.

Why would you say the Dirac implementation is more flexible in the NAD? I had the same perception, but a fine member of this forum refuted that thought. I was making that statement since the C658 could see independent channels (L, R, Sub 1, Sub 2) and use Dirac for correction, while the SHD would only see L and R. Happy to read your thoughts.
Thanks again.-

 

[bluefuzz]

the C658 could see independent channels (L, R, Sub 1, Sub 2) and use Dirac for correction, while the SHD would only see L and R.

This. Whether it makes any any audible or measurable difference is of course debatable.

 

[Dathzo]

This. Whether it makes any any audible or measurable difference is of course debatable.

Thank you @bluefuzz

 

[Dathzo]

Got the C658 and so far so good. Setup was easy, integrated my sub and level is working perfect fine. Fingers crossed it stays that way.

I have a quick question:
I have run Dirac Live (I measured my 2 speakers + sub separately) and have created the filters. I did all of this with a crossover at 80Hz. My question is, what happens if I change the crossover from its value at 80Hz? If I choose 120Hz, for example, would I mess my Dirac filter? Trying to understand the way that the C658 works.
Thank you in advance.-

 

[whitfc]

Got the C658 and so far so good. Setup was easy, integrated my sub and level is working perfect fine. Fingers crossed it stays that way.

I have a quick question:
I have run Dirac Live (I measured my 2 speakers + sub separately) and have created the filters. I did all of this with a crossover at 80Hz. My question is, what happens if I change the crossover from its value at 80Hz? If I choose 120Hz, for example, would I mess my Dirac filter? Trying to understand the way that the C658 works.
Thank you in advance.-

Does MQA still work with Dirac?
Can you configure the crossover range say from 60Hz to 80Hz etc?

 

[Dathzo]

Does MQA still work with Dirac?
Can you configure the crossover range say from 60Hz to 80Hz etc?

MQA works fine with Dirac. You can set the crossover from 40 to 200Hz

 

[whitfc]

MQA works fine with Dirac. You can set the crossover from 40 to 200Hz

Surprising and impressive that the final unfold of the MQA still works after the Dirac filter has been applied.
I meant can you set the lower and upper cut over values of the crossover? I.e. can you control the slope of the cutover?

 

[Dathzo]

Surprising and impressive that the final unfold of the MQA still works after the Dirac filter has been applied.
I meant can you set the lower and upper cut over values of the crossover? I.e. can you control the slope of the cutover?

You cannot set slopes. Nad C658 uses a Linkwitz-Riley filter design for their crossovers which are very similar to Butterworth. The main difference is that Butterworth crossovers have a 3dB bump at the crossover point, whereas Linkwitz-Riley crossovers are flat. The Linkwitz-Riley filter is 24db/octave for both HPF and LPF

 

[Dathzo]

I own the C658. While it does sound good when streaming Tidal or local music from network. It has a ton of bugs. Subwoofer output is almost silent. Pops and clicks coming from the speakers and sub when no music playing. Audible hiss if you get closer to speakers. Very large latency on analog inputs (500ms). Mine is connected to NC400 monoblocks and Focal Aria 906 speakers. I wich I new better before buying it/


You simply cannot trust commercial reviews:

https://www.whathifi.com/reviews/nad-c-658

https://hometheaterhifi.com/reviews/amplifier/nad-c-658-bluos-streaming-dac-review/

https://www.soundstagesimplifi.com/...iews/107-nad-classic-c658-bluos-streaming-dac

https://www.stereonet.co.uk/reviews/nad-electronics-c-658-bluos-streaming-dac-review

I've seen 6 different reviews before buying and all of them praised it... go figure...



P.S. what seems to be the problem with the digital inputs exactly? Mine are functioning OK. The same goes for the HDMI module. If they cant sync, how are they functional and play music w/o a problem (except when the sample rate is changed between songs, then you get a pop sound)

@EB1000, did you manage to remove the hiss? I also listen to it when getting closer to the tweeter and in silent songs, it gets pretty annoying.
Thanks

 

[EB1000]

@EB1000, did you manage to remove the hiss? I also listen to it when getting closer to the tweeter and in silent songs, it gets pretty annoying.
Thanks

I barley notice the his. I think it was fixed by one of the FW updates. There are now two major problems: Low subwoofer output, and clipping distortion on some tracks when subwoofer is enabled. Basically, subwoofer outputs are useless.

 

[Dathzo]

I barley notice the his. I think it was fixed by one of the FW updates. There are now two major problems: Low subwoofer output, and clipping distortion on some tracks when subwoofer is enabled. Basically, subwoofer outputs are useless.

Thanks. My unit does not suffer from low sub output. It is definitely sufficient with my sb1000 pro at -20 gain and even tamed by Dirac, there is plenty of low frequencies there

 

[mig]

Hello,
I'm happyI found this forum.
I have a subwoofer but personally I only use it for home cinema it is connected to my home cinema amp.
I have a msi5 amp and the c658 with sonus faber sonneto 8's for stereo music.
The Dirac didn't really convince me, even after I bought a micro mini dsp, because I found that it made the sound too flat and lost a lot of information, especially in the highs i cann switch with dirac and without dirac and i found more spacialiation without Dirac.
Where the Dirac is interesting is for the bass management, as I use very large columns, by modifying the curve a little more in the zone of 20hz to 35 hz I really get very deep bass. Even if I took the paid version which allows to modify and to correct until 500khz I made a dirac short. I find the c658 very interesting on this point.
And that even by taking amplis much more expensive (I tested an Accuphase e380 one weekend) the sound is practically identical.
Concerning the distortion I know that NAD advises to put the sound at -20 decibels but I find that if we put the sound at -15 or even minus 12.5 we have even more grain in the mediums.
Do you share this opinion or does everyone stay at -20 decibels?
Doesn't the amp and speakers also play a role in the sensitivity and the ability to absorb this distortion?

Cdt
Mig

 

[T.J. Turner]

Hello,
I'm happyI found this forum.
I have a subwoofer but personally I only use it for home cinema it is connected to my home cinema amp.
I have a msi5 amp and the c658 with sonus faber sonneto 8's for stereo music.
The Dirac didn't really convince me, even after I bought a micro mini dsp, because I found that it made the sound too flat and lost a lot of information, especially in the highs i cann switch with dirac and without dirac and i found more spacialiation without Dirac.
Where the Dirac is interesting is for the bass management, as I use very large columns, by modifying the curve a little more in the zone of 20hz to 35 hz I really get very deep bass. Even if I took the paid version which allows to modify and to correct until 500khz I made a dirac short. I find the c658 very interesting on this point.
And that even by taking amplis much more expensive (I tested an Accuphase e380 one weekend) the sound is practically identical.
Concerning the distortion I know that NAD advises to put the sound at -20 decibels but I find that if we put the sound at -15 or even minus 12.5 we have even more grain in the mediums.
Do you share this opinion or does everyone stay at -20 decibels?
Doesn't the amp and speakers also play a role in the sensitivity and the ability to absorb this distortion?

Cdt
Mig

I stick with -20dB. Anything greater and some of my equipment gets distortion. (THX789, Parasound HINT amp)

 

[mig]

Ok thanks

 

[al2002]

A few questions for C 658 users:

1. Are the subwoofer outputs stereo or mono?

2. What are the high and low pass slopes? Are they variable?

3. Can low pass and high pass crossover frequencies be adjusted separately?

Thanks in advance.

 

[Dathzo]

A few questions for C 658 users:

1. Are the subwoofer outputs stereo or mono?

2. What are the high and low pass slopes? Are they variable?

3. Can low pass and high pass crossover frequencies be adjusted separately?

Thanks in advance.

1. Mono

2. The Linkwitz-Riley filter has slopes of 24db/octave for both HPF and LPF

3. No, they are adjusted together and needs to be the same frequency

 

[al2002]

Thanks for the reply Dathzo. Shame about the mono sub outputs.

 

[MKW]

As it is, I would be very curious to A/B the M12 and the C658 to see if there is any audible difference.

As it so happens, I have the M12, C388, Node2i, and between the time I started reading this thread and getting to this page 13/14 of the thread, ordered and received the C658, swapped the HDM-2 MDC card from the M12 into the C658 - and sat for a quick listen (last night). I'm also familiar with miniDSP (a discussion in this thread), and have/used; DDRC-88A/BM, 4x10HD, nanoDIGI 2x8, and 2x4HD - these have been used as crossovers for LXmini speakers and a stereo pair of open-baffle Phoenix (alternate) subs - all Linkwitz designed DIY speakers.

First impressions of the SQ difference between M12 and C658 (without Dirac so far) - M12 wins on natural 'fluid' presentation and stereo separation - I suspect that's due to the AKM DACs, think M12 has separate DAC for each channel (with each 2ch DAC being used in mono to smooth results), lower noise rating, vastly-configurable stereo sub and line outs, and overall better build and other components including case and isolation. Also goes without saying, M12 has a larger, touch-enabled screen, and the menu system is thorough (many more configuration possibilities), and is a genuin pleasure to use.

The C658 has a newer firmware update system (all happens through BluOS update), which is much easier than the old USB-stick system of M12 and C388 generations. Another benefit of C658 is the 5GHz wifi (better connection). Then there is Dirac, which the M12 doesn't have - despite my requesting a Dirac MDC card from NAD on several occasions (as if they care what I want). I find the C658 menu system ready to use, very limited (compared to M12) and overall extremely under-utilized by NAD dev team (pales in comparison even to the previous generation C388 - which does make use of the screen color capability).

In the used market, C658 is selling around $1k, and M12 around $2.5k. Depending on what a person is looking for, both are great units, and both could be so much better with more development time accomplished through firmware updates. So much potential with these products if NAD would allocate more resources to it (especially with the M12). I suspect the C658 is already performing very near its hardware limits (SQ-wise) and suspect the M12 firmware is leaving a lot on the table (which is sad).