Six DAC Comparison

@brbrock  – over on the “What does your DAC sound like” thread, you asked:

"Although you said that the Helene is better can you tell me if the Mystique X SE sounds similar?"

Sorry for the late response, but it has been a busy time for me between trying to put some miles on my bicycle while also dealing with a new (to us) one year-old husky-shepherd puppy.  We have owned 6 huskies over the years, so this is not our first rodeo, but she is a rescue dog and has incredible energy while also requiring a lot of time for acclimation and discipline.

I haven’t posted too much about the Helene yet because I want to be as accurate as possible, and particularly when making any comparisons between it and the Mystique X SE NCZ, which I still own.  However, since you asked, I decided to post my answer here on this thread, where I will be posting further thoughts about the Helene when I am able.

I was not thrilled to have tubes in my system again as I have enjoyed the simplicity of leaving my system powered up all the time, which best matches my sporadic listening schedule.  It also seems that invariably, the best sounding tubes are expensive, hard-to-find, NOS types. I currently have three DACs connected through my Singxer SU6 DDC so I sometimes listen to one of the SS DACs when the Helene is still warming up, which doesn’t take too long.  It took me a while to dial-in different aspects of the Helene, including supports/damping, the specific tubes (the Helene can use multiple tube types), and the tube bias which is user-adjustable and affects the sonic presentation. However, the efforts to get it sounding right are worth it.

In addition to the issues related to having tubes in my system again, there are a couple of ergonomic things I don’t like about the Helene.  The only power switch is located on the back of the DAC, which seems a bit dumb for a DAC that needs to be powered up and down every day.  There is a convenient switch on the top front corner of the DAC that selects optional double reclocking of the digital S/PDIF and AES inputs using the internal Super Clocks of the converter, so it should have been easy to include a conveniently accessible power switch at the same location.  The other thing I don’t understand is the need for the Helene to invert phase, which makes DAC comparisons more time-consuming since the speaker cables must be reversed at the amps when comparing the Helene with phase-correct DACs.  In fairness, once a user settles in with the Helene as their sole DAC, the phase inversion will not be an issue.

Finally, I was a bit side-tracked when I recently purchased Monarchy 22B DAC on a whim to use in my outdoor system.  The Monarchy 22B is a true balanced ladder DAC using a pair of Burr Brown PCM63P-K grade DAC chips.  In my main system, I was floored by how good it sounds, compared to DACs I have here at any price, even though I only paid a few hundred dollars for the Monarchy.  The tone, macro-dynamics, and bass are so good, I am considering performing a major upgrade to hopefully close the gap on the higher level of refinement I hear from both the Mystique X SE and the Helene.  I have enjoyed having it in my main system so much that it may not ever see the outdoor system.

As a brief insight into what I am hearing from the dialed-in Helene, IMO, it just sounds like beautiful music in pretty much every way we want our systems to sound, tone, dynamics, sound staging, clarity, bass impact, texture, and more.  In my system, it does this on all types of music from hard rockers to softer instrumentals, and all types of vocals.   I am not saying it is perfect, or that it would be an end-game DAC for everyone, or even for me, but, in my system it may very well reach a level of performance that begins to eclipse what my other components and room can keep pace with.  I still like the sound provided by my Mystique X SE NCZ and, for those who don’t want tubes, that DAC remains a very nice SS option.  I also very much look forward to hearing Benjamin’s Mystique Z, which he is designing around BB PCM58 DAC chips.  I will post more about the Helene and my comparative thoughts after I can spend more quality time with it.

@fuzzbutt17 I have seen several DAC's now daisy chain DAC chips and seen the Aries-Cerat daisy chain several of the same DAC chips that is in the Mystique DAC's.  Have you thought about doing it in your models.  Is there a pro/con to doing this?  

@mitch2 Thanks for the response on the Helene.  I am in Oklahoma and if you bike you don't have much of a window.  As we get into the summer the temperatures gets up past 100 degrees and in the fall and winter it is very windy so you got to get it in while you can.  There must be a correlation between biking and audio because I have cone across several bikers online.  

I was looking at the internals of the Helene and it is very impressive.  I have seen several companies daisy chain the DAC chips now.  I know Benjamin at Mojo Audio  is moving on to a different DAC chip but I would like to know the benefits of daisy chaining and why he hasn't done that.vv

To answer some of your questions...

Our new Mystique Z will have three inputs: USB, coaxial AES/SPDIF, and TOSLINK. 

Aside from the upgraded DAC chips and upgraded power supplies, we are makings quite a few upgrades to our AES/SPDIF and TOSLINK inputs.

The AES/SPDIF and TOSLINK inputs on the Mystique Z will still use a 100% external clocking source, but we’re adding an active buffering input stage, more advanced hybrid star/plane grounding, and some more advanced filtering stages, to better clean up the digital signal. 

As for multiple DAC chips and "daisy chaining" DAC chips that is a good question. 

One of the big reasons for using multiple DAC chips has always been that it averages any inconsistencies in the individual DAC chips yielding a more linear digital-to-analog conversion. 

That is why it was very common with lower cost lower performance R-2R DAC chips such as the TDA1543 and the AD1865.

Other reasons for using multiple DAC chips have to do with output voltage and output impedance, which tends to be more important with tube than with solid-state DACs. By paralleling DAC chips, designers can often eliminate the need for an additional tube stage and often reduce noise and harmonic distortion. 

At Mojo Audio we take a different approach: rather than using multiple DAC chips we optimize the linearity of the DAC chips we are using. On the R-2R DAC chips we’ve used by Analog Devices and Burr-Brown they have the option of adding a fine-tune adjustment circuit.

Considering it requires a trained technician to adjust these circuits using sophisticated test equipment you can understand why most companies decided to put multiple DAC chips in their DACs to improve performance rather than requiring every DAC they manufactured be burned in and fine-tuned by a technician. 

Now for the really cool news...

The AD1865 and AD1862 DAC chips Mojo Audio has been using have provision for one fine-tune linearity adjustment circuit for the MSB. 

The PCM58 DAC chips we’ll be using in our new Mystique Z has FOUR independent fine-tune adjustments for the MSB, 2nd bit, 3rd bit, and 4th bit. 

No small difference. 

We actually had to invest in an extremely accurate distortion analyzer just to be able to make all of those fine tune adjustments.  

Of course we could have taken the easy way out and saved quite a bit of time and $$$ by using multiple DAC chips "daisy chained" in parallel.

Thankfully, like you, neither manufacturer is considering adding the I2S connection and raising the cost of the end products. It is worth mentioning that it was only last year Antipodes developed a USB output they considered worthy of using and sonically comparable to the AES input. 

Allow me to correct my mistake, Weiss's top end products do not have I2S, however the Antipodes streamers do offer the I2S output.