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After unboxing, I had to let my unit warm up for an hour or two after being sitting outside and literally freezing in 15 degree weather. This was fine for me as I had to re-arrange the audio equipment to put this in place. This unit is replacing my long time Cambridge Audio 840c CDP that I was using as my DAC, which sat on the bottom of my equipment with my Rotel RSP-1098 and RT-1080 on top of it. Knowing how heavy the Pre & Tuner were I didn't want to put the DAC on the bottom, so I rearranged the gear to put the DAC on top of the 1098 and 1080. I also replaced my vibrapods that I had holding the equipment up with a rubber/cork/rubber vibration pads that are better suited to the extra weight of the NAD over the 840c. So once I got that all moved around (which resulted in re-cabling a lot of it) I was ready to see what this DAC could do.
Now I have to say with the unit being refurbished I'm not sure if there would be any type of break in or not.... Now I am one that through buying new equipment I feel there is a break-in time with equipment to either get the unit to perform optimally or for me to get used to the sound. So I basically came into this as it "should be" broken in already, but the sound could change slightly upon further use. So take some of this as you will as I'll be commenting on how over a week or so of using the unit how I feel the sound has changed for me.
Now the M51 is, at this point in time, an "older" DAC compared to the newest ones out there and does not accept DSD streams to it. This, for me, is not a downside as I've got the ability to output the PCM streams...but for some people wanting DSD and all it "does"... that could be some type of issue.
Once I replaced the 840c, I used my BlackSandsAudio Violet Z1 MK2 power cord to power the NAD, ditching the normal power cable that came with the NAD. Again, take it for what you will, but I do feel power cables can make a slight difference, especially over the stock cords, but going much beyond the power cables I have...well I don't see the same return on investment. So I'd have a SUPER tough time going beyond what I paid for the BlackSandsAudio Cable. I also wanted to keep things as similar to the 840c as I could as I just didn't have room to demo back and forth between the two units easily (plus I didn't have a readily available power cable that wasn't stock).
My first impressions were the NAD is more laid back and softer than the 840c that I was very used to. I did feel the M51 had a slightly better midrange to it, but not by much. The upper range is much more forward and present with the 840c which, to me, results in a brighter sound. This initially made me feel that the 840c was more detailed and better at resolving the upper range. The bass on both units was VERY similar and in fact I felt the bass was a little bit more prominent with the CA 840c. Again, this is initial listening to the NAD M51.
I should say that on my CA 840c, I have modified it a little bit by silver soldering all the cables to the connectors to give a better connection. This, I feel, did give a better overall sound to the 840c vs the first couple years I had it. I also replaced the fuses in the unit with slightly better Bussman fuses and got a little bit better sound doing this as well. So this is not exactly a stock 840c.
Now that I've had the NAD M51 in my system for the last week listening to it. I have to say my thoughts on the NAD have changed some. First bass... whatever happened to the M51... something "broken in" or "finally got to optimal performance" About, I would say, the 20 - 30 hour mark, all the sudden the bass just EXPLODED from the unit. The level of bass depth, power, speed, accuracy, and tactility is well... pretty darn impressive. I'm noticing much deeper sound with a lot more power. It's almost like adding a subwoofer to the system....or well... turning the volume up on it at least. There is a lot more energy that I'm getting from my B&W 802Diamonds that I just never got from the 840c. The funny part is it's not on every song, but when songs that you would expect it to have powerful bass, it really stands out and comes alive. Not to the point of being overly annoying...but it's just there in all it's glory. The fact that I didn't have this bass upon using it the first couple days is well... interesting to me because other than break-in, I don't know how to explain it. And it's also not just in my head as I'm feeling it in the couch and table I rest my feet on which I did not get before.
Now on the midrange, especially with vocals, I feel these really have stayed the same as when I first hooked it up. What has changed is my perception that the M51 was weighted in the midrange. It's definitely still sweeter in the mids than the 840c, but it's not at the point of feeling that the response is anything but flat. It just simple does mids better. They have a very smooth sound and yet extremely detailed and life-like. Which, after a couple weeks now, I have to say I'm very much enjoying. The 840c does the mids in a very similar fashion to the M51, and if it weren't for the fact I know the 840c's sound like the back of my hand, i'd probably have had a tough time telling the two apart. The M51 just has a little sense of being boosted in the midrange or well, focusing on the mids more than the 840c does.
In the upper range, where I definitely initially favored the 840c, the M51 has now basically redeemed itself in all aspects. To me, the 840c focuses on the highs in the same aspect where the M51 focuses on the mids. However, after listening to the M51 now, I'm finding that there is no detail lost in the upper range and in fact, might have more information in the highs than the 840c. It's just than the NAD M51 does it much more subtly and probably, for me, was more a re-training of my brain on what I'm hearing and letting go of the "I'm not hearing it all and feel like I'm missing something" that I had to go through. Now that I've gotten through that... I definitely feel that I'm not missing any information in the upper range, it's just a little more mellow (by the slightest bit) and it actually has resulted in a much more enjoyable experience.
The place where I am finding the M51 is the DAC I'm definitely in favor of, is the 3D aspect to everything in the presentation. Now with this, I don't mean that my sound stage has gotten bigger and imaging is better in a 3D space. I mean that there's a fullness to each and every instrument, vocal, and sound that comes from the speakers. The only way I could explain this like this, where before when I listened to a passage of music, if you can imaging a 3D stage in front of you with 2D performers on it. Like cardboard cutouts on stage sitting in a three dimensional space where there is depth to their placement, but not to themselves. It's very much that same feeling that you hear. All sounds have a fullness, roundess, like they have weight and depth and feel to them, more of a sense of lifelike sound to it. The only way I really heard this is by sitting down and really listening to things that I am very familiar with and going back and hooking the 840c to find that it felt very 'flat' compared to the NAD M51.
Another thing that has brought this "3D" sound to the unit and that I just found the other day is using XLR ouputs to my Rotel RB-1090 amp. Using the NAD as my Pre-amp and not the Rotel has brought this out further. Its still there with the unbalanced connections to the 1098, but shows itself better with the XLR right to the AMP. This is with level matching the 1098 on it's output.
I also added an balanced cable from my Musical Fidelity V-Link192 to the NAD at the same time as using the coaxial connection and flipping back and forth (and having someone else do it for me), I was never able to pick up any difference what-so-ever. I even disconnected the coaxial wondering if it wasn't outputting/changing inputs as you didn't get any skip/click/pop at all when switching inputs. So either a balanced connection doesn't make much difference when carrying a digital signal over a coaxial connection or more that the MF V-Link192's outputs are basically identical in what they output. Which I'm perfectly fine with that if that's the case. I'm keeping with the AES/EBU connection, just to say I have it. LOL! This is with using Cardas XLR cables recommended by Jon.
So overall, I have to say this DAC is definitely very impressive!!! The amount of input and output options (having an extremely good digital volume control) really makes the M51 towards the top of just about whatever anyone could want.
The only other much more expensive (4x) DAC that I've gotten some time to listen to was the Bricasti M1 and I'd say the M51 is close to that DAC. Unfortunately, the systems I heard the M1 on.... were far more expensive, so can't say if it was really more the DAC or the system that was as revealing. I'd love for Brian Zolner to be on here and send me a demo unit! ha ha! Or maybe not as then I'd probably want that if I felt it was that much better... so maybe I don't need to go through that.
Anyways, if anyone is looking for, basically, an end-all DAC and doesn't feel the need for DSD... this DAC will give one everything I think they could ever need. It's a heck of a unit and I'm very happy that I took the jump and got it into my system.
The next, which I'll post up, is a HiFi Tuning Supreme fuse is coming for the NAD. It should be here tomorrow or the next day. After a few days with the fuse replaced, I'll post back with my comments on what/if anything the fuse has done.
I did add a HiFi Tuning Supreme fuse to my PSAudio P10 and it made a nice difference in all aspects of the system over it's stock fuse. I also have the HiFi Tuning fuses coming for my Rotel RB-1090 which I can't wait to see what that will do for the amp (if anything)...but I won't replace those until I have a good grasp on the M51s replacement to know what I'm hearing.
So the moral of this story is, if you're looking to spend $2k on a DAC or more... Get this DAC. If you're going to spend 10K+ on a DAC. Still consider demoing this DAC along side those... you might be very impressed with how the M51 compares and at that point judge whether the extra money is worth spending on the more expensive one.
Though as Jon has written for us, the Total DAC definitely seems to be a step up, but again it's in the "next level" of DACs.
