NAD M66 - finally someone makes a decent 2-channel preamp!

[Nocko!]

@pogo:
Hello! Don't mislead the others here:
More than three months ago I told the official NAD support a few faults of the M66:
- no IP-control / RS232 control
- not trigger in functions
- it does not store which screen savers should be used with each input
- you must power cycle the device to store new Dirac slots
- the remote control does not control the brightness of the screen, even though it is described as such in the manual
- too loud switching on noise / "pop", especially at the subwoofer outputs

There are many other defects that other customers have complained about. But I can't report on this myself.

After three months, NAD managed to change something about the standby functionality and perhaps tried to repair the input triggers. Because of the loudspeaker-endangering switch-on noises, I won't even test this anymore. I found a way to work around the faults of the M66 and can live with it for now. But I am still willing to give it back to my dealer as soon as there is another stereo preamp with DLBC or Dirac ART.

The NAD BC1 is the same remote as the one that was delivered with my M66. Apparently it's just "cheaper" built. But that's exactly one of my main criticisms: NAD has attached a (probably) excellent preamplifier to a really bad streamer. Everything depends on the stupid BluOS module. I would rip it out in a heartbeat if this gave me control of the RS232 port, like on my M17...

But is not just the poor remote control. In terms of functionality and missed opportunities the M66 is stll a catastrophe. I'm still very disappointed M66 and I want Stefano to know that too. His Accuphase and Electrocompaniet actually deserve something better than the M66, also from a haptic point of view.
Nocko!

 

[pogo]

NAD will follow a priority list.
The issues you mentioned can probably all be fixed via software.
My assumptions:
The implementation of the new streaming service has the highest priority at the moment. The first harbingers were recently the rollout of new MQA libraries.

 

[Stefano]

Oh, oh...Pogo again... Not sure how much you receive from NAD for your nice marketing...

@Stefano:
The M66 is a disaster to use. As far as I understand Pogo correctly, the M33 is much better in this regard. From the point of usability, firmware and service, I seriously have to advise against the M66. Don't buy it if you want a preamp with decent functionality! See my previous postings.

On the other hand - you have a very interesting system:
I always thought Dirac had trouble with dipoles. Does this work for you or do you use Dirac at all?
If you don't use Dirac, I see absolutely no reason to buy a NAD, especially the M66.

If Dirac works well for you: Do you also use subwoofers or do you want to use subwoofers in the future?
Then the M66 could be interesting for you. Give away the (surely great) Electrocompaniet and the M33. Take your new M66 with a crossover frequency at around 50-70Hz with DLBC activated and one or two really "fast" active subwoofers and keep the Accuphase for your Maggies. Could be interesting.

To get to the point: NAD only makes sense if you want to use Dirac, specifically Dirac Live Bass Control. The rest of the device (and probably all other NAD devices) is rather underdeveloped and sometimes even embarrassing.

So think twice!
Nocko!

Dirac is fine with dipole systems, of course i use it since version 1.xx. Now i've 2 subwoofers my system is 2.2
what is very strange and frustrating is that the M66 has been launched in spring 2023 and they don't have solve all the bugs in 1 and a half year...

 

[Nocko!]

Had to much time yesterday...
If I activate "Analog Direct" on an input - specifically XLR - a signal is routed to the subwoofer. That's ok for now.
Dirac then remains switched on, but in my configuration hardly any bass comes through because Dirac naturally cuts off the room boosts in the bass range.
To get the uncorrected (exaggerated) bass signal, you have to switch off Dirac. Mind you, even though the input is supposedly "Analog Direct"!

So, the specific error is that when you select the “Analog Direct” option, the analog signal is not passed through in an unchanged analog form. Rather, the subwoofer signals (digital by nature) are corrected by Dirac. You can even distinguish the different Dirac target curves even though "Analog Direct" is switched on. The minimum troubleshooting solution would be for Dirac to be switched off when the "Analog Direct" option is selected and then switched on again for the other inputs.

This isn't about the principle either: I need the function advertised with the analogue direct option in order to be able to pass the signal for the front left/right of my surround preamplifier through the M66 unchanged. In this configuration, the surround preamplifier has to do the Dirac equalization and the bass signal cannot be processed twice by Dirac without an accident. I'd rather not even think about the time delay between the subwoofer signal, which has since been digitized, and the "analog direct" signal...

This stupid chaining might also be the reason why I haven't been able to get proper surround sound when the M66 passes through the front channels. Stupid box - I'm thinking about a Stormaudio again, even though I primarily listen to stereo.

Unfortunately, due to the errors and shortcomings of the M66 that have already been criticized, I have also been deprived of the options to install a suitable macro in my home control using TCP/IP. Unfortunately, you cannot create a preset where Dirac is simply switched off. So the whole thing is extremely annoying and unnecessary.

@Stefano:
Thanks for the reply - I like dipole systems. And you are right. The M66 is a quite complicated machine and I can understand that there are a few glitches and that NAD only found these errors through customer reactions after the device is on the market. But with such a long lead time, not noticing that two physical inputs (RS232 / Trigger) are not working is not possible. And the fact that they don't manage to find a solution in the short term is even worse. That's why I can't recommend the device in good conscience.
Nocko!

 

[pogo]

Wouldn't a Marantz AV 10 be better for you?

 

[da Choge]

I'd rather not even think about the time delay between the subwoofer signal, which has since been digitized, and the "analog direct" signal...

I don't know how the M66 "Analog Direct" works. Are all input signals put through BluOS processing regardless of whether they are set as "Analog Direct" or allowed to go through inputs for which Dirac DSP is additionally being applied? Doesn't BluOS processing (to allow multiroom distribution) have a very high latency already (on the order of 50 msec)? Maybe this is why NAD hasn't been able to enact a functional "Home Theater Bypass/Pass-Through" mode? I have no idea if these are even valid questions, but I am concerned about the BluOS delay and the inability to switch it off, if desired.

BTW, it almost seems as if NAD let's their customers do all the hardware & firmware Beta-testing and then they come out with a V.2 version a couple of years later

 

[pogo]

This shows the pure analog path very well:

 

[da Choge]

This shows the pure analog path very well:

View attachment 398094

Looks alright; no BluOS processing for Analog Direct; that would be very good. Where did you get these linear renditions of the circuitry path?

 

[pogo]

 

[pogo]

From my point of view, such a box makes more sense than an HT bypass: Link

 

[katsu]

At 14:57 the comparison of the Cyrus is with the NAD m66: Terry

 

[pogo]

Cyrus with BluOS
The sound description of the M66/M23 is very appropriate.

 

[Hear Here]

This shows the pure analog path very well:

View attachment 398094

Where did you find that diagram? Unfortunately is is rather poor resolution and I'd like to see a clearer version. I've googled "NAD M66 block diagram" with no success. Could you post a link please?

As I understand it, Analogue Direct keeps the signal analogue throughout, so DL / DLBC CANNOT have any influence on the signal because these DSPs (the D in DSP gives a clue) require the signal to be digitised. Therefore I suspect that Noko! has somehow got his signal digitised along the way. If he disconnects all this HT stuff and simply connects his vinyl player signal directly into the M66 and engages Direct Analogue, DL will have no effect on that signal - it simply cannot!

Whether the M66's optional tone controls will affect the analogue signal I cannot say - that depends on whether the tone controls are done digitally or directly to the analogue signal.

 

[Nocko!]

Wouldn't a Marantz AV 10 be better for you?

Yes, totally.
But I neither like the design of Marantz devices nor am I a big fan of the brand.
But objectively you are absolutely right, the AV10 would be technically perfect at first glance.

I'm in a "technician forum" here, so this is actually nonsense, but for me a device that's in my living room always has to have something tactile or special to it that appeals to me. This could be a design gimmick, nice material or color or simply no design at all. Unfortunately, this is not the case with Marantz or Denon. I know, stupid argument...
Nocko!

 

[pogo]

But I neither like the design of Marantz devices nor am I a big fan of the brand.

Then just wait until next year. There should be a successor to the M17. The T799 might also be an option.

 

[Hephaestus]

Where did you find that diagram? Unfortunately is is rather poor resolution and I'd like to see a clearer version. I've googled "NAD M66 block diagram" with no success. Could you post a link please?

As I understand it, Analogue Direct keeps the signal analogue throughout, so DL / DLBC CANNOT have any influence on the signal because these DSPs (the D in DSP gives a clue) require the signal to be digitised. Therefore I suspect that Noko! has somehow got his signal digitised along the way. If he disconnects all this HT stuff and simply connects his vinyl player signal directly into the M66 and engages Direct Analogue, DL will have no effect on that signal - it simply cannot!

Whether the M66's optional tone controls will affect the analogue signal I cannot say - that depends on whether the tone controls are done digitally or directly to the analogue signal.

This one is clearer:

Link:
https://www.audio-supply.com/article/nad-m66-hiav/

 

[pogo]

Where did you find that diagram?

In this thread. The diagram is mounted inside the M66, see also the picture above.
Of course, the signal remains analog in analog mode up to the L/R outputs. The analog signal is also tapped in parallel and runs via the digital part, which still operates the subwoofer outputs in parallel.

 

[Nocko!]

I don't know how the M66 "Analog Direct" works. Are all input signals put through BluOS processing regardless of whether they are set as "Analog Direct" or...

Very good question!

The picture that Pogo posted shows a module as it is installed in my M66. Since I may be returning the device, unfortunately I can't unscrew it to take a better photo.
But I don't really understand the signal routing based on the picture:
If you follow the path "Line in L&R Balance", the analog signal behind the "Relay Switch" is also tapped for the BluOS module. Beforehand it is definitely digitized, and before the subwoofer outputs it is converted back again.
I don't see where Dirac works, but I suspect it's in the BluOS module. But I think we agree that Dirac works exclusively digitally. And you can hear that in the subwoofer signal, even though that's exactly what should be avoided with "Analog Direct".

@Hear Here:
Unfortunately I don't have any vinyl player at hand but I think we don't need one here. "Analog Direct" isn't an input but a function you can switch on with all analog inputs. So if I opt for "analog direct" I expect that the analog input signal is not touched in any way. This seems to be true for the pure left and right signal (I haven't measured this). But in addition to the pure left and right signal the M66 gives me a digital corrected signal for my subwoofers (at this point - perhaps someone else can check this ! Perhaps I am making some crude mistake here...).

So what I get in total is not an analogue, unprocessed signal, but a mishmash of a clean stereo signal and a digitally altered subwoofer signal.

Regardless of whether you - like me - have enormous problems when you want to implement a "home cinema bypass" or whether you just want to listen to your good old vinyl record unadulterated: you don't get a pure analog signal, but something else.

So there is no "Analog Direct" if you are using subwoofers. I think Pogo will recommend to switch off the subwoofers...
Nocko!

 

[pogo]

So there is no "Analog Direct" if you are using subwoofers

If you use passive subwoofers like I do, you'll be fine. This is also possible for speakers with integrated active subwoofers.

 

[Nocko!]

If you use passive subwoofers like I do, you'll be fine. This is also possible for speakers with integrated active subwoofers.

Hi Pogo - this part I don't understand...
The M66 pretends to output an analogue, unadulterated signal. But it doesn't. It adds something at another output. So at my listening position everything is mixed up, both in terms of frequency response and in terms of time.
If I have to switch off my subwoofers for "Analog Direct", then please let NAD write that down in the instructions (or disconnect the subwoofers themselves in this case). It took me weeks to realize what goes wrong here...

Nocko!