[Sonic Defender]

  Normally you wouldn't need digital volume control (or software vol ctrl in my case) if you are using a headphone amp (i.e. pre+power amp).  HE-6 needs the power of a speaker power amp (with no vol ctrl).  And I have tried several approaches (lightspeed passive attenuator and DCB1 buffer preamp) and in the end I like no-preamp foobar-vol-ctrl sound best.  It seems to confirm that wtih 24-bit dept even -30dB software vol ctrl does not hurt my music (large-scale soundtrack, classical, new age, etc)
 
Still, I always worry about forgetting turning down foobar volume.  A DAC with digital volume seems make a lot of sense for me.  

Gotcha, I run my HE 560 directly from speaker tap cables, I hear the HE-6 responds extremely well to this technique. Anyway, I run my 560 from a 180watt amp with not a problem, right from the speaker terminals.

 

[sasbyte]

what adapter are you using from speaker amp to he560.

 

[Sonic Defender]

  what adapter are you using from speaker amp to he560.

Custom cable made by Norne Audio, worth every penny. Couldn't be happier with it.

 

[Faultline]

That's great news on the distortion fix!
 
Do you know what version of firmware has the fix (1.50 perhaps)?  I'm running 1.41.  I can't find any release notes on 1.50.
 
Background:
 
I got the NAD M51 as an upgrade over an Emotiva XDA-1 DAC and there was a definite improvement so I kept it and sold off the Emotiva.  Unfortunately, I found that in the "Fixed" volume setting driving my Pass Labs XP-20 pre-amp over balanced cables, it was distorting BADLY.  
 
If I backed off the gain, the distortion would diminish to inaudible levels.  I did not think that was quite right and was worried that the NAD was defective.  Much back and forth with NAD and Pass Labs ensued.  End of the day, I had to "settle" for backing off the gain to -6 (distortion was gone at -5, but I took it down to -6 to avoid distortion which might have cropped up on hotter sources).  
 
Pass Labs said the XP-20 should not be overdriven based on NAD's published specs for the M51 but it obviously was (either that or the M51 was being overdriven internally before sending signal out).  Running other devices as inputs to the Pass Labs XP-20 preamp over balanced cables caused no distortion.  This included the Emotiva XDA-1, a Musical Fidelity M1 DAC, and a Benchmark DAC1.  
 
A discovery:
 
If you are in the market for a $2,000 DAC, you owe it to yourself to hear the Chord QuteHD (now QuteEX).  It's a significant improvement sound-wise over the M51.  (I saw a posting in this thread where somebody preferred the _feel_ of the NAD over a Marantz -- if heft is important to you then the QuteHD is NOT your thing).  Very straightforward A/B testing resulted in immediately obvious, repeatable improvements that everybody who's heard this A/B test has picked up immediately.  The listeners are not told what device they were listening to.  But when the signal path was through the QuteHD, the sound was "clearer", "less veiled", "more present in the room", and "less scratchy and harsh"...  I've been through a lot of DACs and never heard better.  QuteHD leaves the M51 in the dust.  I suspect the current QuteEX is either the same or better.
 
I've kept both the M51 and the QuteHD.  I use the NAD for exploring music or streaming content via a Google Chromecast Dongle because it outputs over HDMI only.  I also kept the NAD because I use a Pioneer transport to play formats that require HDMI out (SACD).  The NAD has 2xHDMI in and that's the only reason I'm keeping it.  Everything else is played through the QuteHD.

 

[vlach]

That's great news on the distortion fix!

Do you know what version of firmware has the fix (1.50 perhaps)?  I'm running 1.41.  I can't find any release notes on 1.50.

Background:

I got the NAD M51 as an upgrade over an Emotiva XDA-1 DAC and there was a definite improvement so I kept it and sold off the Emotiva.  Unfortunately, I found that in the "Fixed" volume setting driving my Pass Labs XP-20 pre-amp over balanced cables, it was distorting BADLY.  

If I backed off the gain, the distortion would diminish to inaudible levels.  I did not think that was quite right and was worried that the NAD was defective.  Much back and forth with NAD and Pass Labs ensued.  End of the day, I had to "settle" for backing off the gain to -6 (distortion was gone at -5, but I took it down to -6 to avoid distortion which might have cropped up on hotter sources).  

Pass Labs said the XP-20 should not be overdriven based on NAD's published specs for the M51 but it obviously was (either that or the M51 was being overdriven internally before sending signal out).  Running other devices as inputs to the Pass Labs XP-20 preamp over balanced cables caused no distortion.  This included the Emotiva XDA-1, a Musical Fidelity M1 DAC, and a Benchmark DAC1.  

A discovery:

If you are in the market for a $2,000 DAC, you owe it to yourself to hear the Chord QuteHD (now QuteEX).  It's a significant improvement sound-wise over the M51.  (I saw a posting in this thread where somebody preferred the _feel_ of the NAD over a Marantz -- if heft is important to you then the QuteHD is NOT your thing).  Very straightforward A/B testing resulted in immediately obvious, repeatable improvements that everybody who's heard this A/B test has picked up immediately.  The listeners are not told what device they were listening to.  But when the signal path was through the QuteHD, the sound was "clearer", "less veiled", "more present in the room", and "less scratchy and harsh"...  I've been through a lot of DACs and never heard better.  QuteHD leaves the M51 in the dust.  I suspect the current QuteEX is either the same or better.

I've kept both the M51 and the QuteHD.  I use the NAD for exploring music or streaming content via a Google Chromecast Dongle because it outputs over HDMI only.  I also kept the NAD because I use a Pioneer transport to play formats that require HDMI out (SACD).  The NAD has 2xHDMI in and that's the only reason I'm keeping it.  Everything else is played through the QuteHD.

Thanks for sharing...always wondered how the QuteHD performed, that's really good to know!

 

[Sonic Defender]

I'm really enjoying the M51 so far. Significantly different from the Gungnir that is for sure. The M51 seems faster to me, but I think that and other sonic differences I'm noticing can be explained by less bass (but also less congested bass) than the Gungnir. The detail retrieval and instrument separation with the M51 seems quite a bit better.
 
The NAD also seems to have a strong central placement with more depth to the soundstage, but the central placement strength I suspect is more related to how the album is mastered. So was the M51 a significant upgrade over the Gungnir? For me I would have to say so as I'm now hearing more of everything (except bass quantity). I'm quite willing to trade off some bass quantity for more articulate bass and early on it seems apparent to me that the M51 is the better DAC overall. I loved my Gungnir quite a bit, but now I feel that a little muddiness has been lifted. I worried that losing some softness would be an issue, but so far so good. Not to mention the NAD looks really sexy beside my M3 integrated.
 
I get what an earlier poster was saying that there is less impact with the M51, but while I hear that, I still like it very much. A very even-handed DAC. The lower bass quantity will slightly lessen the feeling of fullness of sound at quieter volumes as compared to the Gungnir which was prolific at bass. The Gungnir was also very capable of producing quality bass, it wasn't a ham-fisted brute DAC at all, very accomplished in it's own right. I'm sure there will be people who prefer more bass grunt power than the M51 provides, but people who like non-glare detail retrieval will love the M51. I'm surprised at how much I'm noticing now, even as I type so not sitting here listening for differences, almost unattended listening now.

 

[olor1n]

Your impressions of the M51 vs the Gungir match my own experience. Bass was one of my favourite aspects of the Gungir's presentation and whilst I found the M51 to have a touch less in terms of quantity, it more than makes up for it not just in the quality of the lower registers but also in the extra refinement across the board.

 

[Danny86]

  I'm really enjoying the M51 so far. Significantly different from the Gungnir that is for sure. The M51 seems faster to me, but I think that and other sonic differences I'm noticing can be explained by less bass (but also less congested bass) than the Gungnir. The detail retrieval and instrument separation with the M51 seems quite a bit better.
 
The NAD also seems to have a strong central placement with more depth to the soundstage, but the central placement strength I suspect is more related to how the album is mastered. So was the M51 a significant upgrade over the Gungnir? For me I would have to say so as I'm now hearing more of everything (except bass quantity). I'm quite willing to trade off some bass quantity for more articulate bass and early on it seems apparent to me that the M51 is the better DAC overall. I loved my Gungnir quite a bit, but now I feel that a little muddiness has been lifted. I worried that losing some softness would be an issue, but so far so good. Not to mention the NAD looks really sexy beside my M3 integrated.
 
I get what an earlier poster was saying that there is less impact with the M51, but while I hear that, I still like it very much. A very even-handed DAC. The lower bass quantity will slightly lessen the feeling of fullness of sound at quieter volumes as compared to the Gungnir which was prolific at bass. The Gungnir was also very capable of producing quality bass, it wasn't a ham-fisted brute DAC at all, very accomplished in it's own right. I'm sure there will be people who prefer more bass grunt power than the M51 provides, but people who like non-glare detail retrieval will love the M51. I'm surprised at how much I'm noticing now, even as I type so not sitting here listening for differences, almost unattended listening now.

Try the Yellowtec Puc 2 Lite AES>EBU converter, it enables you to use the best input of the M51 (usb is quite average) and increases dynamics and bass quite considerably. 
 
I am a very happy owner. As AES EBU cable I use DH labs D-110, no need to spend more.

 

[Sonic Defender]

  Try the Yellowtec Puc 2 Lite AES>EBU converter, it enables you to use the best input of the M51 (usb is quite average) and increases dynamics and bass quite considerably. 
 
I am a very happy owner. As AES EBU cable I use DH labs D-110, no need to spend more.

I was looking at the Puc 2 Lite just last week. I'm not sure I'm convinced that for that significant cash outlay I would be able to hear the difference. For sure with devices like that I would need to hear from people who have used blind listening tests to demonstrate the difference is audible. I just have a hard time believing that the USB is so challenged that it is missing all kinds of information to the point where entire broad frequency ranges are attenuated. That said, I am also curious to know if it really is true and technically I do not know why these devices couldn't make this kind of improvement. You should have a friend help you do a blind listening test. That would be great and virtually nobody ever does this with any of their gear around here.
 
Hope that doesn't come off wrong, I do appreciate the suggestion, and I also have an open mind, but as I said, for that kind of money I totally need a little more before I can justify the expense. Cheers.

 

[olor1n]

I'm in the same boat and am curious about the supposed improvements over the M51's usb interface. I'm looking at the Gustard U12 as a cheaper entry point. Has anyone used the U12 with the M51?

 

[Somnambulist]

If you search around a bit on various forums you can find individuals claiming x input sounds better to them than the other ones - be that HDMI, USB, AES, etc. Make of that what you will.

 

[Sonic Defender]

What I'm experiencing is almost like getting off an addiction. Going from the very strong bass of the Gungnir to the leaner bass of the M51 will take an adjustment period. Ultimately I will need to decide what is the more accurate portrayal of bass, the powerful Gungnir depiction, or the tighter more agile M51. I suspect the M51 is the more accurate of the two. Now I may find my headphone selection needs to be tailored to the new sound signature of the M51 meaning perhaps bass heavy headphones such as the TH900 are needed. Man is the M51 a fast sounding DAC! The decay is really fast which ultimately I think helps combat bloat and frequencies bleeding into each other. 

 

[wink]

I am very suspicious of any gear that gives plenty of loose bass.  That's not how I hear live bass producing musical instruments.
 
The looseness of the bass could be caused by the amp not delivering enoiugh instantaneous current to the headphones.

 

[Sonic Defender]

  I am very suspicious of any gear that gives plenty of loose bass.  That's not how I hear live bass producing musical instruments.
 
The looseness of the bass could be caused by the amp not delivering enoiugh instantaneous current to the headphones.

Are you talking about the Gungnir? My amp is a very solid little NAD powerhouse rock stable at 8 and 4 ohm output so it certainly has nothing to do with the amp. The Gungnir is well known to have very powerful bass. I don't think live is the standard to judge studio music anyway myself, plenty of room effects at play. I have attended many a concert in my day including orchestral, rock, choral in many different size venues. I think live sound should be used to judge live albums, studio albums will not sound like live recordings very often, and with electronic instruments there is no real acoustic/live sound anyway as they require electronic amplification/processing anyway to produce a sound, and that is before the board crew does their thing.

 

[wink]

True, but still, an electronic should emulate a real instrument.
 
If it doesn't it is defective.
 
If a bass machine produces wooly bass, then it is either defective or intentional.
 
If intentional, then the matter becomes the quest to provide the same amount of wooliness, bur Not more.