• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

NAD M33 Streaming Amplifier Review

pogo

Major Contributor
Joined
Sep 4, 2020
Messages
1,241
Likes
382
Real on/off button at the back that can completely shut off the power supply. Can be handy when the M33 display does not show up or the audible volume does not react on volume adjustments, which occasionally happens. Using the on/off button always solved it.
I have never had that before!?

I would prefer a decent working remote.
Try the Bluesound RC1.
 

ruderik

New Member
Joined
Feb 18, 2022
Messages
2
Likes
1
I recently purchased an M33, and besides using it to listen to music, I also use it to send the audio output from my TV to external speakers. The problem I’m having is that there is a delay in the audio to where it is very noticeably out of sync with the video. I didn’t have this problem with my prior all analog amplifier. The problem occurs regardless of whether I use the optical output from the TV or the analog output. Having the A/V Mode function of the M33 off or on makes no apparent difference. Does this sound like a defect with my M33, or is there possibly a setting on the M33 that I need to change?
I'm experiencing a similar issue. Delay of >300ms between line-in and output of the M33. Tried all kinds of settings regarding the input (A/V mode, sample rate, etc). Also tried with Dirac off. Issue remained. What solved it for me was to do a factory reset of the M33.
I used this video as reference: https://www.youtube.com/watch?v=4S5KBlieT0I
My setup: NVidia shield (playing the video) --> HDMI --> Marantz 7011 --> pre-out --> M33. As a reference I made a setup with pre-out Left connected to the M33 and right to my Rega Elicit-R (analog) direct in. M33 had a very large delay, Rega (of course) no delay.
Like mentioned, I performed a factory reset, then the problem was gone. After reloading a Dirac profile to the unit, the problem re-appeared again. Switching back and forth between Dirac profiles "off" and "myprofile" seemed to influence the delay, and possibly, after switching a lot, solve the issue. Also a reboot after switching Dirac profile seemed to solve the delay issue.
 

Pragmatic

Member
Joined
Feb 19, 2022
Messages
16
Likes
3
So, I just got an M33 a few days ago. Lots of positives, but I have an issue with the max volume level that I have never encountered before in any amp (and this is my first expensive amp). There's simply little to no headroom to speak of. My speakers have 90db sensitivity, which should be more than adequate for an amp of this caliber.

I have mine hooked up to the TV via optical, but have also set up a network share on my server for my FLAC library, and the SPL when streaming or going through the TV is identical. If I listen to classical music for example, I usually settle at 80% volume, but 90% is no problem either, when sitting just 2,5 meters away. And 90% is the absolute max after I set up Dirac.. On my previous amp, a mediocre 2x150W NAD C375BEE, max I ever had the volume was around 40%, and that was probably a bit louder than the max volume on the M33..

Is this just a modern amp thing, where the manufacturers don't trust the users to be able to regulate the volume? My speakers aren't monsters either (B&W 702 Signatures), but they still have more to give than the amp allows. They're down in 4 ohm territory in the low freqs, so the amp should in theory be able to deliver more than they can handle (300W peak). I also measured the power output of the amp, directly from the wall, and max I ever saw was around 60W, at 80% volume (sans Dirac and tone controls). There's nothing about the sonic performance that leads me to believe anything is wrong either - it drives the speakers well.

I currently have 4 amps in the house, 3 NAD and a small Denon, and even the little Denon at 2x30W has plenty of headroom to the point where I don't even know how high the volume wheel goes after 4 years. Tried googling this issue several times, but apart from people mentioning that Dirac and Tone controls subtract x amount of max volume on this particular amp, I've found nothing.

I like the amp, but paying $6000 to handicap my speakers' SPL isn't what I had in mind. To be clear, I don't listen at max volume all day long, just a few songs here and there. And my hearing is fine too.
 

pogo

Major Contributor
Joined
Sep 4, 2020
Messages
1,241
Likes
382
First of all you should switch the volume display from % to dB. After that I would check if the volume limit is set to 0dB (max level). This is also what the % value is based on and can be confusing from time to time. I would also activate the digital VU meter for the input sources to check if the input level is sufficient.
 

Pragmatic

Member
Joined
Feb 19, 2022
Messages
16
Likes
3
First of all you should switch the volume display from % to dB. After that I would check if the volume limit is set to 0dB (max level). This is also what the % value is based on and can be confusing from time to time. I would also activate the digital VU meter for the input sources to check if the input level is sufficient.
I prefer the volume in %, since I changed it from the default (100% is max, doesn't get easier than that in my mind). No limits in place, checked that several times. VU meter is active on all sources. My favourite classical pieces reach pretty close to 0 db at the highest peaks, so that's fine. But classical music being what it is; very dynamic, makes it kind of an issue.

I could switch off Dirac and get another 10%, since it doesn't do all that much in my treated room, but it still helps a bit. Just find it very odd that an amp at this level has such a low max volume. Let's say I had speakers with very low sensitivity, say 84db - I don't see how that could work at all on the M33.

In most cases, the max volume is sufficient, but I feel like the amp has stifled my speakers. Not looking to blow them, but sometimes it's fun to test the limits. I could of course return it and get, say, a Hegel H390 instead, but I loathe the ugly design on them, and the simple display and lack of functions that the M33 has. But for all I know, the Hegel could have the same issue - if this is just the way new amps are designed.
 

pogo

Major Contributor
Joined
Sep 4, 2020
Messages
1,241
Likes
382
That's a strange thing. Here in Germany, similar observations have been made recently. A humming noise was also once perceived within the M33. The serial number range was around H219M33!?
 

Pragmatic

Member
Joined
Feb 19, 2022
Messages
16
Likes
3
H21XM33 here. My unit produces a very slight electronic hum or hiss, but I have to place my ear within 1-2 cm of the unit to hear.
I'm pretty sure that my unit is normal, so far at least.
If I may ask, what kind of volume levels do you use (on what db sensitivity speakers) max? Would be useful to get a reference.
 

EJF

New Member
Joined
Feb 11, 2022
Messages
3
Likes
0
I'm experiencing a similar issue. Delay of >300ms between line-in and output of the M33. Tried all kinds of settings regarding the input (A/V mode, sample rate, etc). Also tried with Dirac off. Issue remained. What solved it for me was to do a factory reset of the M33.
I used this video as reference: https://www.youtube.com/watch?v=4S5KBlieT0I
My setup: NVidia shield (playing the video) --> HDMI --> Marantz 7011 --> pre-out --> M33. As a reference I made a setup with pre-out Left connected to the M33 and right to my Rega Elicit-R (analog) direct in. M33 had a very large delay, Rega (of course) no delay.
Like mentioned, I performed a factory reset, then the problem was gone. After reloading a Dirac profile to the unit, the problem re-appeared again. Switching back and forth between Dirac profiles "off" and "myprofile" seemed to influence the delay, and possibly, after switching a lot, solve the issue. Also a reboot after switching Dirac profile seemed to solve the delay issue.
Thank you ruderik for sharing your discovery. Using the youtube video you referenced, I found that my delay was also around 300ms. I did the factory reset and the delay is now essentially gone. I haven't reloaded my Dirac profile yet. If switching Dirac off and on makes the delay worse, this will be a short term solution. I often listen to music in the late evening hours using headphones so as not to disturb others, and that requires manually turning off Dirac, which I then have to manually turn back on when listening through the speakers. I don't know why that's not handled by software, since the M33 can automatically sense the headphones to turn off the speakers.
 

pogo

Major Contributor
Joined
Sep 4, 2020
Messages
1,241
Likes
382
I often listen to music in the late evening hours using headphones so as not to disturb others, and that requires manually turning off Dirac, which I then have to manually turn back on when listening through the speakers. I don't know why that's not handled by software
In my case, switching to another DL slot would be beneficial, as I also use DL to equalize my HP.
 

pogo

Major Contributor
Joined
Sep 4, 2020
Messages
1,241
Likes
382
what kind of volume levels do you use (on what db sensitivity speakers) max?
If I play the song 'I know' from this album at volume setting -20dB and DL enabled, that is already an unhealthy volume:
Link

Distance to the LSP is approx. 3m @ speaker sensitivity 87dB / 8ohms
I measure with a H/W SPL meter a max. level of 98dB(C) at my listening position.
I made another level measurement under REW with UMIK-2 incl. cal data:
spl_1137617.jpg

The H/W SPL meter with analog meter showed 2dB less (98 to 100). Fits quite well.

Normally I listen in the volume range of -30...-40dB;)
 

pogo

Major Contributor
Joined
Sep 4, 2020
Messages
1,241
Likes
382
I just see that your B&W are specified at 46Hz - 28kHz ±3dB. A direct comparison is not possible, since my LSP are so specified:
fg_1139550.png

Source: Teufel
 

Pragmatic

Member
Joined
Feb 19, 2022
Messages
16
Likes
3
If I play the song 'I know' from this album at volume setting -20dB and DL enabled, that is already an unhealthy volume:
Link

Distance to the LSP is approx. 3m @ speaker sensitivity 87dB / 8ohms
I measure with a H/W SPL meter a max. level of 98dB(C) at my listening position.
I made another level measurement under REW with UMIK-2 incl. cal data:
View attachment 187936
The H/W SPL meter with analog meter showed 2dB less (98 to 100). Fits quite well.

Normally I listen in the volume range of -30...-40dB;)
I don't have average measurements on my db-meter, but at a first glance, I'd guess that it's more than here when I play a song at 80% volume, which should be the same level. And I have 3db higher sensitivity speakers too. Strange. I'll have to make some measurements using REW.

Thanks for this point of reference, very helpful.

Edit: Changed volume to db, set it at -20, hooked up the included NAD measurement mic, calibrated SPL using my external db meter and played the entirety of the song Rapunzel which you linked, with Windows and YouTube Music volume at max. Results below. Speakers are approx 2,35 meters from my listening position (measured from the front of the speakers, not from the middle). My external db meter showed on average a lower SPL than the NAD mic - so not sure what's up with that. At any rate, your setup clearly produces higher SPL, even though I have 3db higher speaker sensitivity.

By the way, this is a completely flat (in theory - no additional gains anywhere) Dirac curve at 20-500hz, subwoofer turned off. Widest focus, for an entire couch. And I have 8 acoustics boards of various shapes, sizes and functions which probably dampen the overall SPL.
So many factors to consider, but this was a fun experiment if nothing else :)
1645355096633.png
 
Last edited:

ruderik

New Member
Joined
Feb 18, 2022
Messages
2
Likes
1
Thank you ruderik for sharing your discovery. Using the youtube video you referenced, I found that my delay was also around 300ms. I did the factory reset and the delay is now essentially gone. I haven't reloaded my Dirac profile yet. If switching Dirac off and on makes the delay worse, this will be a short term solution. I often listen to music in the late evening hours using headphones so as not to disturb others, and that requires manually turning off Dirac, which I then have to manually turn back on when listening through the speakers. I don't know why that's not handled by software, since the M33 can automatically sense the headphones to turn off the speakers.
Yesterday I found out that switching to a digital input and back to line-in also solves it. Digital input does not have to be connected.
 

Pragmatic

Member
Joined
Feb 19, 2022
Messages
16
Likes
3
It is not the same for me, i.e. -20dB corresponds to 67% for me!?
Well, I was wrong about 80. -20 is 75% for me. But that's very peculiar! In that case, you have way more headroom than me. Must be some kind of auto sensing circuit on the amp, but what factors it considers, is beyond me. I am limited to a 10A circuit in my listening space, and my power purifier, but that's 2300W, so I don't see how that could be a problem when the peak effect is 900W on the M33.
 

pogo

Major Contributor
Joined
Sep 4, 2020
Messages
1,241
Likes
382
I would remove the power purifier and perform a factory reset.
According to NAD such devices should also generally not be used with the Class-D amplifiers!
I have found an interesting article about 3-4 years ago on the old NAD homepage. Unfortunately, this article is no longer available on the new homepage and I therefore asked again regarding the M33:

...
Q:
In your old service section I once read that no mains filters or buffers may be used for the new Class-D amplifiers. Where can I find this article and is this still valid?

A:
Regarding the line current filter for digital amplifiers - it is not recommended, because the filters can lead to losses in sound quality for the digital amplifiers. Unfortunately, we no longer have the corresponding article from the NAD sales department at the time.
...

This is probably due to the fact that the Class-D do not always get the required current in time due to the additional time constant of the filter.
 

Pragmatic

Member
Joined
Feb 19, 2022
Messages
16
Likes
3
I would remove the power purifier and perform a factory reset.
According to NAD such devices should also generally not be used with the Class-D amplifiers!
I have found an interesting article about 3-4 years ago on the old NAD homepage. Unfortunately, this article is no longer available on the new homepage and I therefore asked again regarding the M33:

...
Q:
In your old service section I once read that no mains filters or buffers may be used for the new Class-D amplifiers. Where can I find this article and is this still valid?

A:
Regarding the line current filter for digital amplifiers - it is not recommended, because the filters can lead to losses in sound quality for the digital amplifiers. Unfortunately, we no longer have the corresponding article from the NAD sales department at the time.
...

This is probably due to the fact that the Class-D do not always get the required current in time due to the additional time constant of the filter.
Well shit, it's almost brand new, and cost like $5-600. I have very dirty power with a ton of noise in my living room, due to several UPS units running 24/7, computers, big heat pump running 24/7 and so on. It made a significant difference when I bought it (for a class AB amp). I'll give it a try, I guess.

Thanks for the suggestion.

Edit: tried removing it (it's an Isotek Evo 3 Polaris, and I only connect the amp, nothing else), and hated the sound. No more volume either. I think I just have too much crap connected to the same fuse / wiring. Was worth a try though.
 
Last edited:

Pragmatic

Member
Joined
Feb 19, 2022
Messages
16
Likes
3
I would remove the power purifier and perform a factory reset.
According to NAD such devices should also generally not be used with the Class-D amplifiers!
I have found an interesting article about 3-4 years ago on the old NAD homepage. Unfortunately, this article is no longer available on the new homepage and I therefore asked again regarding the M33:

...
Q:
In your old service section I once read that no mains filters or buffers may be used for the new Class-D amplifiers. Where can I find this article and is this still valid?

A:
Regarding the line current filter for digital amplifiers - it is not recommended, because the filters can lead to losses in sound quality for the digital amplifiers. Unfortunately, we no longer have the corresponding article from the NAD sales department at the time.
...

This is probably due to the fact that the Class-D do not always get the required current in time due to the additional time constant of the filter.
I called the dealer where I bought the amp, and asked about power purifiers. They were quite insistant that it can make a positive difference also in Class D and digital amps. I made it clear I already have one, so there was no additional sales in it for them. They had tried a high-end AudioQuest Niagara filter on a NAD M22 (also Class D) and experienced significant improvements.
They also told me that Lyngdorf, another amp manufacturer, officially state that aftermarket power cables don't do anything on their amps. So, manufacturers make many strange claims. If you have a power purifier yourself, you may want to try it on your M33.

I asked about the max volume too, and they said that the volume control on the M33 is very linear, contrary to many older amps where it often is not (lots of gain the first 50%, then very little after that). Their demo model was lent to a customer, so they couldn't check their dB -> % values.
Well, I have a 6 year warranty through the shop, so there's not much to worry about.
 

Calou

Member
Joined
Feb 20, 2022
Messages
29
Likes
5
I called the dealer where I bought the amp, and asked about power purifiers. They were quite insistant that it can make a positive difference also in Class D and digital amps. I made it clear I already have one, so there was no additional sales in it for them. They had tried a high-end AudioQuest Niagara filter on a NAD M22 (also Class D) and experienced significant improvements.
They also told me that Lyngdorf, another amp manufacturer, officially state that aftermarket power cables don't do anything on their amps. So, manufacturers make many strange claims. If you have a power purifier yourself, you may want to try it on your M33.

I asked about the max volume too, and they said that the volume control on the M33 is very linear, contrary to many older amps where it often is not (lots of gain the first 50%, then very little after that). Their demo model was lent to a customer, so they couldn't check their dB -> % values.
Well, I have a 6 year warranty through the shop, so there's not much to worry about.
So, I just got an M33 a few days ago. Lots of positives, but I have an issue with the max volume level that I have never encountered before in any amp (and this is my first expensive amp). There's simply little to no headroom to speak of. My speakers have 90db sensitivity, which should be more than adequate for an amp of this caliber.

I have mine hooked up to the TV via optical, but have also set up a network share on my server for my FLAC library, and the SPL when streaming or going through the TV is identical. If I listen to classical music for example, I usually settle at 80% volume, but 90% is no problem either, when sitting just 2,5 meters away. And 90% is the absolute max after I set up Dirac.. On my previous amp, a mediocre 2x150W NAD C375BEE, max I ever had the volume was around 40%, and that was probably a bit louder than the max volume on the M33..

Is this just a modern amp thing, where the manufacturers don't trust the users to be able to regulate the volume? My speakers aren't monsters either (B&W 702 Signatures), but they still have more to give than the amp allows. They're down in 4 ohm territory in the low freqs, so the amp should in theory be able to deliver more than they can handle (300W peak). I also measured the power output of the amp, directly from the wall, and max I ever saw was around 60W, at 80% volume (sans Dirac and tone controls). There's nothing about the sonic performance that leads me to believe anything is wrong either - it drives the speakers well.

I currently have 4 amps in the house, 3 NAD and a small Denon, and even the little Denon at 2x30W has plenty of headroom to the point where I don't even know how high the volume wheel goes after 4 years. Tried googling this issue several times, but apart from people mentioning that Dirac and Tone controls subtract x amount of max volume on this particular amp, I've found nothing.

I like the amp, but paying $6000 to handicap my speakers' SPL isn't what I had in mind. To be clear, I don't listen at max volume all day long, just a few songs here and there. And my hearing is fine too.
Hello all, first post.

I've owned the M33 for a year now and I've experienced similar issues with the gain, I've tried to solve the issue with the support but after a lot of email exchange we did not find a root cause for the problem.

My observations is also that with Dirac and tone control enabled at the same time the loss of master gain is the most significant I've ever experienced with an integrated amplifier. I own a Marantz SR6013 which I've used with Audyssey and an Icepower 1200 and never experienced such a gain reduction while using the different features.

I've also experienced that after some Dirac calibration there is additional gain loss depending of how much Dirac corrects the original speaker measurement and changing the dirac correction filter to follow the original improves slightly the available power on the master gain. Unfortunately turning Dirac off doesn't seem to restore the gain to factory settings, nor performing a simple factory reset in my case. I usually have to perform a full firmware installation via USB to get back to an acceptable master volume level.
Using Dirac seems to trigger the gain issues in my case and I always end up reverting to factory settings. I don't really need Dirac since I've a dedicated room optimised for music but I do appreciate the additional control provided by Dirac on Bass.

I mostly use Tidal (connect) as my source and I've been trying to understand how Tidal loudness normalization works in combination with Bluos track and Album gain in order to find out if some settings combination can add another handicap to the master gain. I've found this interesting article but I don't know yet if this is affecting gain management on the M33.

I'm still very happy with the M33, the sound quality is the best I've experienced so far, It's a beautiful integrated amp. I was glad that I could use the balance control with Dirac after going crazy trying to achieve a centered image in my setup (always to the left). The recent fix of the tone controls finally makes it usable (without Dirac). It's just annoying that the software can have such a negative impact on the sound in some cases. Gain management is still a mistery to me, it's normally loud on POP, but on classical music or songs with high dynamic range I also end up turning the volume to -15db and with Dirac enabled this doesn't leave a lot of margin for a close to realistic listening experience.
 
Last edited:
Top Bottom