NAD M51 Direct Digital DAC Impressions
Jan 13, 2013 at 8:54 AM Post #631 of 1,623
Sounds like a poorly designed piece of kit for the price. 
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Jan 13, 2013 at 9:00 AM Post #633 of 1,623
Quote:
As mine was burning in, I thought there was very little burn-in change compared to some DACs I've had. After about 300 hours I noticed that it was more relaxed and that it had changed character. But again it wasn't as big a change as with other equipment.

I've also found it sounds better through my external tubed preamp than using the built in digital attenuation. (!?)

Also found its susceptible to incoming noise on the USB and spdif inputs (getting rid of electrical noise before it arrives improves it a lot). its also susceptible to noisy power (likes shielded power cords and up front passive filtration).

 
I use a USB converter to AES/EBU so no noise for me.  I also haven't noticed any power related noise.  
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Jan 13, 2013 at 11:23 AM Post #635 of 1,623
I use a USB converter to AES/EBU so no noise for me.  I also haven't noticed any power related noise.  :blink:
Have you experienced the lack of noise for reference to notice? Power isolation transformers are good for digital gear. Removing the RF and other frequencies inducted into power lines lets the DAC power supply do it's job better. Usually relates to a quieter background and better imaging. Apartment living shares a lot of common noise throughout the wiring of the building. If you notice your gear sounding better at night, you could use some power conditioning. IMO
 
Jan 13, 2013 at 11:26 AM Post #636 of 1,623
Quote:
Have you experienced the lack of noise for reference to notice? Power isolation transformers are good for digital gear. Removing the RF and other frequencies inducted into power lines lets the DAC power supply do it's job better. Usually relates to a quieter background and better imaging. Apartment living shares a lot of common noise throughout the wiring of the building. If you notice your gear sounding better at night, you could use some power conditioning. IMO

 
 
Well HC as you know all I have are the Emotiva Power Cords at the moment.  At this point I hear no noticeable noise.  I'll compare once I get one of those isolation transformers.  As for right now I would have to say to difference will be very subtle.  We'll see.
 
Jan 13, 2013 at 3:26 PM Post #637 of 1,623
Well HC as you know all I have are the Emotiva Power Cords at the moment.  At this point I hear no noticeable noise.  I'll compare once I get one of those isolation transformers.  As for right now I would have to say to difference will be very subtle.  We'll see.
:veryevil: the journey continues down the hobbyhole. :wink:
 
Jan 15, 2013 at 4:00 PM Post #638 of 1,623
-1dB
 
Jan 20, 2013 at 5:33 PM Post #639 of 1,623
I've been having some issues with my M51 when feeding my SRM-717 through balanced cables.  The thought at this time is that I'm getting some DC that is tripping the 717 protection.  I have a message into NAD and I plan to try and measure the output to see if I can confirm it.
 
Outside of that I am very happy with the M51 and hope to resolve this so I can continue to enjoy it!
 
Chris
 
Jan 22, 2013 at 11:05 AM Post #640 of 1,623
Quote:
I've been having some issues with my M51 when feeding my SRM-717 through balanced cables.  The thought at this time is that I'm getting some DC that is tripping the 717 protection.  I have a message into NAD and I plan to try and measure the output to see if I can confirm it.
 
Outside of that I am very happy with the M51 and hope to resolve this so I can continue to enjoy it!
 
Chris

 
Hmm...that's disconcerting.  Consider posting in the Stax thread.  Maybe some help over there.  Please keep us posted.
 
Jan 22, 2013 at 1:40 PM Post #641 of 1,623
Thanks, already tapping into those guys too... A few things to note:
  1. I never had any issues using the RCA out
  2. I added some 10db attenuators into the line and I have not had a drop out since, I've played the combo for hours now with no issues, sounds great
  3. There have been no other issues with my other amps, everything runs fine, sounds great
 
A few M51 owners pointed out that you need to be careful of the XLR wiring as it can be different in different parts of the world.  I have to admit I did not check this and it could be related.  I need to check the diagrams on the back of the M51 and the 717 to see what differences there are if any on my particular units.  You can can see a little of that discussion here: http://www.head-fi.org/t/223263/the-stax-thread-new/20715#post_9081200
 
Jan 24, 2013 at 4:37 AM Post #643 of 1,623
would you kindly compare it to your PWD mk2?
 
Jan 27, 2013 at 3:37 AM Post #644 of 1,623
OK, NAD is here.
First impressions, amazing piece.
Tried all the inputs with same recording, despite i don't use USB in my opinion is the best.
I connect hdmi CA 751BD throug denon in bypass mode and works fine.
My friend took his dac, Resonessence  Invicta 4000 USD, to test with nad and the results are very good for nad.
It cames close to it in every formats.
 
Note: Resonessence  with DSD input file is simply amazing.
 
NAD cames to stay.
 
Jan 27, 2013 at 3:52 AM Post #645 of 1,623
Tats good to hear, invicta is an incredible sounding DAC. I'm thiking of buyin m51 and comparing to my nfb7.32 sabre dac. I'm hoping it will be a moderate improvement.
 

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