This is a review and measurements of the NAD M17 V2 Home Theater Surround Sound 11.1 channel preamplifier and processor ("pre/pro"). It is kindly loaned to me by one of our members. The M17 V2 is a high-end unit, costing US $6,600.
Unlike a lot of AVRs and processors I have tested, the M17 V2 oozes audio luxury with a very attractive enclosure and gorgeous display:
As much as I love and appreciate the work that went into the aesthetics of the unit, it reminds me of a review of BMW 7 series. It said, "this drives so well it is a shame that the owner will likely sit in the back and let someone else drive it." By the same token, in a home theater application you want a dark room and likely will hide this beautiful piece of audio machinery hidden some place.
The display is not only beautiful and large, it is also very informative. I very much appreciated the constant indication of audio and video resolution and format. The former allowed me to catch a very strange anomaly in the way my PC was sending audio to it which I fixed. This information is always available inside these processor and AVRs. It is a shame they don't always display it.
The screen is touch sensitive although I mostly used the remote control for control. The remote is super heavy and long. I know they wanted to give the feeling of quality but I take a more ergonomic plastic one over this. There are sharp corners and I would worry about dropping it and denting a wood floor, or breaking a glass table. Minor complaint.
Here is the back panel:
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In my opinion balanced XLRs are mandatory in any audio product that claims to be high performance and there are here of course. That is what I used for my testing. For inputs, I focused on Audio 1 analog input and HDMI. The processor happily synced with my computer and passed through its "4K" resolution through without affecting its frame rate. Researching online though, I saw some complaints about HDMI compatibility. Such things are unfortunately a fact of life with HDMI, more so on some products than others.
Processor DAC Audio Measurements
It was with much anticipation that I powered on the unit and ran my dashboard tone of 1 kHz/24-bit through it:
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For balanced XLR outputs, stand-alone DAC usually output 4 volts or more. This is half as much so I boosted the volume to +6 dB to get that:
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That got me the 4 volt I needed and gave a boost to the performance of the M17 V2. It increased its SINAD (signal over noise and distortion) to 96 dB. This is all dominated by high second harmonic distortion and just a bit of noise. Can't imagine the DAC they are using has this much harmonic distortion so likely this is the amplifier buffer/gain stage or analog switcher that is causing it. That is my guess at least until NAD chooses to communicate with us and explain why an audio product costing over $6000 can't outperform a $9 apple phone dongle. As it is, the M17 V2 does well relative to other tested AVRs and processors:
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In the larger context of all DACs of different types tested so far, the overall ranking is underwhelming:
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I hope one day we see one breaking into green bucket. Not holding my breath on blue (top class).
Jitter and spurious noise performance shows poor hygiene when it comes to the design:
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The larger picture is the first measurement which clearly shows some symmetrical components which usually indicate jitter. Later, I happen to run this test again (inset) and notice how the spikes to the left have completely changed! This shows that internal activity in the unit is bleeding into the output of the DAC. This could be HDMI picture related content, microprocessor servicing front panel or other sources. Either way, I would be unhappy if a $100 DAC did this let alone such an expensive processor. Fortunately the levels are below -110 dB so not an audible concern. It is like a hanging nail. You are not going to die from it but it sure is annoying to see.
Here is what the background noise level looks like with no signal driving it:
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Shouldn't be seeing power supply related noise. The spike at 1 kHz should not be there either. The curve up is fine and is part of the noise shaping in the DAC to push noise into inaudible range. There is however a spike all the way to the right that should not be there. Its level is -76 dB or so. As such, any measurement that includes that much bandwidth will show that, instead of true distortion. Such is the case when we run our THD+N versus frequency with bandwidth of 90 kHz:
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Lowering measurement bandwidth to 45 kHz (green) eliminates that factor. But noise shaping still increases the overall THD+N. And whatever other distortion may be there. Overall, it is a poor showing with respect to controlling ultrasonic content and distortion.
Dynamic range is "decent" clearing 16 bit content:
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Frequency Response is flat to in audible band and extends quite a bit indicating lack of resampling when all effects are turned off:
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Here is the filter response for each sample rate supported over HDMI:
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Yet again we see levels are reduced the higher the sample rate becomes. Why? 192 kHz is some 7 to 8 dB lower in volume.
Multitone test (32 tone signal) replicates what we already know as far as distortion:
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Linearity is poor relative to what even $100 DACs can produce:
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Investigating that at 1 kHz, the level would constant go up and down. Even averaging it didn't help. So it is both noise and deterministic error.
Intermodulation distortion versus level was reasonably good:
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Since I ran this test at +6 dB, most optimal volume control level is around -2 dB although the penalty is quite light in going beyond that to 6 dB.
Analog Input Audio Measurements
In case you are tempted to use an external DAC and feed it to the M17 V2, I performed a few measurements of that. The M17 is nice in that it gives you a choice of sampling rate so I set it to 192 kHz (highest rate) and here is what we get:
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I was surprised how low the output level was at 0 dB volume. I am feeding it 2 volts, how come I am not getting 2 volts out? I had to boost the level to nearly max of 25.5 dB to get to 4 volts out:
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Overall performance does not change though, producing a very disappointing 73 dB SINAD. This is a throw-away input suitable for perhaps an old game console or your VHS player. I jest of course but come on. How can you have so much harmonic distortion here? We are taking a 23 dB hit by feeding the unit analog instead of digital signal. Noise I could understand going up but distortion?
Needless to say, intermodulation distortion versus level was quite horrible:
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To cover all bases, I also tested with volume control set to 0 dB and there, the very low output level reduces performance (green).
Frequency response test confirmed high sampling rate was indeed used:
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One bright spot was crosstlak versus frequency:
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Conclusions
The good looks of the NAD M17 V2 is undeniable. Proper homework and investment in tooling and case was made to produce a truly gorgeous product. No doubt this compelled me to go easier on the measurement result, giving it the "good" pink panther moniker. But really, in the context of producing a clean, 12 channel DAC with processing NAD fails with M17 V2. No wonder they provide no specifications whatsoever on performance of the DAC. Either they don't measure it or measured it and know it doesn't make for good marketing. We are talking DAC performance that barely matches the
Pioneer VSX-LX504 AVR. A processor is designed to give better performance than an integrated AVR.
Once again as I have noted in the past, the DIrac Room EQ is a major plus here and should in practice produce excellent sound. Just don't go around bragging to your friends that you have a best design audio/video processor. So much low-hanging fruit was left in the design of M17 V2.
These companies need to hire an anal audio performance czar to review the product and have veto power over its release. Only then are they going to make progress toward making excellently engineered products. There can be strong competitive advantage for the first home theater company that gets there.
FYI I also have the companion power amplifier to test.
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As always, questions, comments, recommendations, etc. are welcome.
The owner wants this back very soon so I have to drive it to him. Roundtrip this is nearly 200 miles. I need gas money folks! So
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