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NAD C658 Streaming DAC Review

Puddingbuks

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I do notice that I need to shut of Dirac when I plug in my headphones, not a major issue but more of an oversight in my opinion. I just looked at the M33 and it looks sweet, but it is missing something that I would love to have, which is a record output (either analog or digital). There is no way to get the output of the built in BluOS Node to feed anything else. I have a control system in my house with distributed audio and control. If I just had a way to get the output of the Node to the input of my distributed audio system (at a fixed level), it would be perfect. Currently I need to add a second Node for that functionality. Another thing that I don't understand about the C658 is that is has a full color display, but they don't take advantage of it. The only time you see anything in color is when it turns on! Maybe we will see an update in the future. I am using mine with a March Audio amp and love it.
The Darko review on the m33 point at the two way bluetooth, where you can also send audio from the m33 to another device.
 
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This is a review and detailed measurements of the NAD C658 streamer and DAC. It also acts as a preamplifier with Phono and line in. A cool feature is inclusion of Dirac Room EQ and balanced out and you get a killer feature set. For that, you need to pay though to the tune of US $1,650. The owner purchased a factory refurbished which I see going for US $1,300.

The overall design looks quite nice with a larger and informative display:


Here is the back panel:

View attachment 54654

The only feature missing that should be there is the unit acting as a USB DAC. It has a USB connector but that is it acting as a host, playing content from external storage.

Since there is no USB input, I started my testing with Coax S/PDIF. To my surprise, the frequency counter on Audio Precision was jumping all over the place as was the waveform. This indicate lack of lock on the incoming clock which could either be a design flaw or something broken in this unit.

I then switched to Toslink optical with the same result. Wanting to make sure my analyzer had not failed, I powered another DAC and it worked perfectly there.

Without these inputs working, the only digital path I had was streaming using Roon which worked fine. Roon complains that it is not certified but worked anyway.

Streaming DAC Audio Measurements
Here is our usual dashboard:

View attachment 54655

Even though performance bests the specification at 0.005% distortion, this is well below acceptable in a high priced device like this:

View attachment 54656

The only other test I can run this way is jitter:
View attachment 54657

That spray of spikes should not be there. Fortunately it is at -130 dB so not an audible concern.

Conclusions
Shame to see quality control or design issues in a brand like NAD. Even if the digital inputs were not broken, the performance of the DAC fails to even match a half decent $9 phone dongle. So despite great feature set, NAD needs to go back to the drawing board and clean up its implementation.

Needless to say I can't recommend the NAD C658.

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As always, questions, comments, recommendations, etc. are welcome.

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I have just bought this unit NAD C658. I am absolutely clueless to your reviews. I have just finished setting the unit up. Got it acting as a Pre-amp to my Rogue Audio Magnum Atlas Power Amp. Turntable - Technics SL-1500 with the Ortofon Blue stylus, Yamaha CD-S2000 and speakers are KEF LS50.
The set-up process was a breeze with DIRAC LIVE and BluOS on my iPad Air.
The sound from the turntable, CD player and in-house server to my ears are clear sharp with good bass. I don't have any fancy words like most of these audio magazine reviewers.
My point here is, you can use all kinds of spectro testing equipments to test all these audio equipments. The bottom-line that matters is our individual ears on how we perceive the sound.
I LOVE the unit and I highly recommend to anyone who is looking for a pre-amp with streaming capability and a built-in DAC. I am also very pleased with the price point.
 

Alexanderc

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I have just bought this unit NAD C658. I am absolutely clueless to your reviews. I have just finished setting the unit up. Got it acting as a Pre-amp to my Rogue Audio Magnum Atlas Power Amp. Turntable - Technics SL-1500 with the Ortofon Blue stylus, Yamaha CD-S2000 and speakers are KEF LS50.
The set-up process was a breeze with DIRAC LIVE and BluOS on my iPad Air.
The sound from the turntable, CD player and in-house server to my ears are clear sharp with good bass. I don't have any fancy words like most of these audio magazine reviewers.
My point here is, you can use all kinds of spectro testing equipments to test all these audio equipments. The bottom-line that matters is our individual ears on how we perceive the sound.
I LOVE the unit and I highly recommend to anyone who is looking for a pre-amp with streaming capability and a built-in DAC. I am also very pleased with the price point.
Glad you like it; lots of people here do. There are only a couple of products on the market that do what this does for the price. For myself, I’ve just read too many accounts of this particular product not working correctly, requiring frequent factory resets, etc. to consider it. I have no doubt that if it’s working properly it sounds just fine.

Unlike most of the audio media, the testing that goes on here is really about showing objective data and demonstrating the level of engineering in a product. This forum is not trying to tell anyone which electronics sound the best.
 
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I have just bought this unit NAD C658. I am absolutely clueless to your reviews. I have just finished setting the unit up. Got it acting as a Pre-amp to my Rogue Audio Magnum Atlas Power Amp. Turntable - Technics SL-1500 with the Ortofon Blue stylus, Yamaha CD-S2000 and speakers are KEF LS50.
The set-up process was a breeze with DIRAC LIVE and BluOS on my iPad Air.
The sound from the turntable, CD player and in-house server to my ears are clear sharp with good bass. I don't have any fancy words like most of these audio magazine reviewers.
My point here is, you can use all kinds of spectro testing equipments to test all these audio equipments. The bottom-line that matters is our individual ears on how we perceive the sound.
I LOVE the unit and I highly recommend to anyone who is looking for a pre-amp with streaming capability and a built-in DAC. I am also very pleased with the price point.
There have been many firmware updates to the C656 since those early reviews that have adressed most of the major issues. So you arent technically listening to the same product as the early reviewers.
 
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has anyone seen any measurements of this elsewhere? I am curious if this is just a case of a defective unit. I am hearing many bugs have been fixed via firmware.
 

JDRCapeCod

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has anyone seen any measurements of this elsewhere? I am curious if this is just a case of a defective unit. I am hearing many bugs have been fixed via firmware.
I am not sure of other sites with measurements, but I can tell you that mine has been running bug free and I love the sound of it.
 
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@WoodyTobiasJr : In post #163 in this thread, Dave54321 gave the following link to another review that provided some measurements:

https://topnewreview.com/nad-c-658-streaming-dac-review/

As Dave noted, the measurements are not as thorough as Amir's (and the thumbnail graphics shown are so small as to be unreadable). But they give no indication of any issues, which does indeed suggest a defective unit. As I noted in an earlier post, the provenance of a "factory refurbished unit", the one originally measured here, may be dubious. It's also possible that there was an earlier problem with signal locking as Amir reported, but that a firmware upgrade fixed it.

As to other reported bugs, my experience mirrors JDRCapeCod's: bug free, sounds great. Room correction, included with the 658, really is a game changer.
 
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Got my C658 today and it sounds incredible together with my C298 power amp, and that is without Dirac which really is needed in my room. The biggest flaw I have found so far is a really serious one: it is not possible to set max volume. One slip of a fat finger in the app and your speakers are toast (in my case not so cheap Harbeth Super HL5 Plus). Unbelievable that they have missed that.
 

SIY

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Got my C658 today and it sounds incredible together with my C298 power amp, and that is without Dirac which really is needed in my room. The biggest flaw I have found so far is a really serious one: it is not possible to set max volume. One slip of a fat finger in the app and your speakers are toast (in my case not so cheap Harbeth Super HL5 Plus). Unbelievable that they have missed that.
If you're using BluOs, there is indeed a way to do that.
 

Attachments

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I fat-fingered the remote once on my Pixel 3a. Fortunately, my speakers withstood the few seconds of full blast with a 300 w per side amp (yikes!) until the I got to the off switch. In fact, the power amp fuse blew, which must have happened about the time I hit the switch. I subsequently switched over to using an old Moto G4 that was lying around -- a several year old phone with a more accurate touch screen than the Pixel. (Thanks Google....) No problems since.

This episode did *not* involve the volume control that appears near the bottom of the screen when something is playing; I've never had an issue with that, and you would really have to slide your finger a long way off base to max that one. But the volume control is replicated in a much smaller area, and consequently a much shorter distance to slide, if you open the "Player" icon at the top right of the screen; that's the one that I bumped while trying to close that little window.

Of course, if you're truly nervous about the possibility, you could use the NAD remote's volume control -- but I certainly admit that this would be a kludge.

The sort of good news is that the functionalty presumably can be added via software. Sounds like a good thing to suggest to NAD. They have been updating the BluOS app at a good pace.
 

caesar

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I got in contact with NAD because of the missing volume limit feature for the C 658. The response was, that the feature was initially implemented but led sometimes to problems with input sources. Therefore the feature was removed. But it is still planned to add the feature again in the future if all problems can be solved.

I think chances are good, they provide the feature with future updates. But what if the problems can not be solved.? I don't know. Seems like with the C 658 a product was released which is still under development.
 
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I fat-fingered the remote once on my Pixel 3a. Fortunately, my speakers withstood the few seconds of full blast with a 300 w per side amp (yikes!) until the I got to the off switch.

if you open the "Player" icon at the top right of the screen; that's the one that I bumped while trying to close that little window.
The same exact thing happened to me the other day but on iPhone. I jumped out of my listening chair faster than Usain Bolt to simultaneously spin my hardware volume knob and turn my system off. Thankfully no lasting damage. But scary enough that I will never ever use Bluetooth to cast music from my iPhone to my stereo system and I will never use the software volume slider, either. Remote control for me always. I always turn down the volume in between albums and sources. And I use the mute button also. But only after I’ve turned the volume down to -60dB or less.
 

JCG

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I have enjoyed reading these posts. They helped me decide to buy the C658, even though the measurements might not be great. I have some pretty nice powered Dynaudio monitors, but placement is not optimum, and I listen off-axis mostly. I was pretty sure I wouldn't be able to discern the shortcomings that the measurements indicated, as long as there is no stuttering, distortion, or dropouts. The C658 replaces a Node2 which was making weird noises when used as a Roon player, although it was working fine with Spotify Connect, Tidal Connect, and other services. I haven't tried Dirac yet, but I think the C658 sounds better than the Node2, and no strange behavior so far. Haven't tried the phono section, but that is one of the reasons I chose the C658.
 
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I have had the C658 for three weeks now....and I must say it is getting on my nerves. I run it with the C298 power amplifier and Harbeth HL5+. I now find it harsh, bland and it is not "fun" to listen to it. It is going back.
 

caesar

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What do you think about placing a CD-Player on top of the C658? I know it would be better to place the C658 on the CD-Player, but unfortunately this is not possible because the CD-Player is smaller in depth. The C658 does have the ventilation slots on top. So obviously it would be better to keep them completely free. Between the C658 and the CD-Player is still about 2cm or a finger thick of space.
In the manual NAD writes minimum distance of 10cm to right/left, backside and top. But on marketing photos of NAD i saw equipment stacked like this amp / C658 / CD-Player.


Is this really critical for a preamp? I guess it wont get as hot as a amp does. What are your thoughts? Could this harm the C658?

Thank you in advance.
 
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I have enjoyed reading these posts. They helped me decide to buy the C658, even though the measurements might not be great. I have some pretty nice powered Dynaudio monitors, but placement is not optimum, and I listen off-axis mostly. I was pretty sure I wouldn't be able to discern the shortcomings that the measurements indicated, as long as there is no stuttering, distortion, or dropouts. The C658 replaces a Node2 which was making weird noises when used as a Roon player, although it was working fine with Spotify Connect, Tidal Connect, and other services. I haven't tried Dirac yet, but I think the C658 sounds better than the Node2, and no strange behavior so far. Haven't tried the phono section, but that is one of the reasons I chose the C658.
Hi, how did you get on with your C658 and the Dynaudios? Did the Dirac setup improve the sound?

I have Dynaudio Xeo 6 actives, and am looking for a good preamp/streamer/DAC/headphone amp to use with them. I've read this entire thread. At first I thought "no way I'm getting this" but by the time I hit page 12 I was more relaxed. It's always the way with modern tech gear, and they seem to need up to a year of firmware updates to settle down.
 
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I found another measurement and a look inside. Unfortunately same results as here. And the used parts are not that good. But I am unable to have an opinion on that due to lack of knowledge. Maybe get someone involved in this thread who does. https://www.stereo.net.au/forums/topic/325667-nad-c658-measurements-and-teardown-q/
Interesting thread. After reading the OP's first 16 posts, I was convinced he was preparing to toss the unit out with the trash. Then he said something I didn't expect.

"at the end of the day no matter how I look at it there's no streamer/dac/preamp/dsp all in one box on the market in this or anywhere near price category so if anyone is looking for one which does all of this in one box I think C658 is no brainer"
 
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