Review and Measurements of Grace Design m900 DAC & Amp

[Hugo9000]

Maybe it would be interesting to contact Grace Design and ask why these measurements are what they are.
The weird ones. Maybe they could say what is going on.
Most of the time they are pretty open.

He already contacted them, see his post here:

https://www.audiosciencereview.com/...e-design-m900-dac-amp.6470/page-2#post-144148

 

[Bliman]

He already contacted them, see his post here:

https://www.audiosciencereview.com/...e-design-m900-dac-amp.6470/page-2#post-144148

Ah ok. Sorry I missed that.

 

[Paolo Piaser]

I can get one @ $280 (EUR), is it fair as a second hand price ? (A 2017's MassDrop unit.)

I think so. Consider all Grace Design prpducts have the 20 years warranty or the 5 years one. So it would be 3 more years for a unit that performs better than others in a number of thing. Not an expert here, but other options are topping DX3 pro or ProJect S2, in the same price range and new.. If you don't need the unit to be usb powered, measurements says it is 'better' the dx3 pro.

 

[amirm]

Maybe it’s the “spurious tones”, but for the J-Test, are you using the +/- 250Hz LSB sidebands?

Yes.

 

[amirm]

Maybe it would be interesting to contact Grace Design and ask why these measurements are what they are.

I contacted them after I post the review.

 

[Ron Texas]

Maybe it would be interesting to contact Grace Design and ask why these measurements are what they are.
The weird ones. Maybe they could say what is going on.
Most of the time they are pretty open.

It's witchcraft.

 

[amirm]

FYI I ran some FFTs at low frequencies and distortion is definitely higher as the THD+N vs Frequency shows. Early harmonics are raised quite a bit compared to other DACs. So I think "this is what it does." I will be shipping the unit to its owner tomorrow by the way....

 

[amirm]

@amirm sorry if from time to time I go back with the same question, but I don't understand the linearity test results in general... For instance here the linearity test is superb, while in DX3-PRO is no so good (dominated by noise floor starting at 90 db), though DX3 has a lower noise level than m900 as shown in this review in the intermodulation test. Can you help me in understanding?
Thanks

Sure.

Linearity is a measure of single frequency voltage accuracy. A very sharp narrowband filter gets rid of all but the tone generated in digital domain. Instability in this voltage due to noise, or power supply ripple, etc. will cause linearity to suffer differently than normal measurements. In other metrics, entire bandwidth of audio or more is used so what ails them does not correlate with linearity and vice versa.

Put simply, linearity is a vertical measurement of accuracy (with the dimension being volts). THD, DNR, etc. are an area of measurement of volt by frequency spectrum.

Going back to your answer, as a broadband measurement, DX3 Pro does better than many other DACs. But with respect to measuring just voltage at this one frequency, its value seems to fluctuate as we get lower and lower resulting in that exponential rise.

 

[rajapruk]

Did the tested unit have the latest firmware installed? (version 2.4 released 5/11/2018 on Grace website https://gracedesign.com/support-documents/)

 

[graz_lag]

As I look at your set-up beneath every post, I notice you are not easily satisfied.

Ha Ha !!! I am pretty consistent in keeping the materials I like, and the ones that are not easy to move as the loudspeakers and amplifiers ...
After discovering this site, it has become totally different for the DACs instead !
There are dozens of solutions, which offer superlative values for money out there to discover, besides the common brands I was used to look at.
For example, I am currently replacing my Weiss INT204 USB/SPDIF interface with the F-1 interface from Singxer, @ an 8th of the value !

 

[Roen]

I have one almost that large to use if power goes out from a storm. Nearly all of these 5V battery packs use switching power supplies, so I don't see any likely improvement in SQ, and never heard one with mine. The M900 does not have an on off switch, so the battery will discharge if you forget and leave it connected.

Even with a SMPS, I believe Amir has shown objective measurement improvements on DACs that are sensitive to power issue. It seems to lie in between wall warts and Linear Power Supplies, being closer to Linear.

 

[Roen]

I like the way they've done the volume here. Pretty much digital to your standard 2v out for 0 db FS, and some useful analog gain which won't compromise SNR for those who could use more. I wish more devices worked like this.

Benefits of this type of design?

 

[Ron Texas]

Even with a SMPS, I believe Amir has shown objective measurement improvements on DACs that are sensitive to power issue. It seems to lie in between wall warts and Linear Power Supplies, being closer to Linear.

Someone tested a bunch of them at Audiophile Style a while back. An Apple wall wart was cleaner than some battery pack. You may want to make generalizations, but you do so at your own risk. Implementation is a big part of the end result.

 

[Roen]

Someone tested a bunch of them at Audiophile Style a while back. An Apple wall wart was cleaner than some battery pack. You may want to make generalizations, but you do so at your own risk. Implementation is a big part of the end result.

I see.

If you have a link or search terms that I can look for besides Audiophile Style wall wart battery pack, that would be appreciated.

 

[Ron Texas]

I see.

If you have a link or search terms that I can look for besides Audiophile Style wall wart battery pack, that would be appreciated.

If I had the link it would be here. Just go there and look. The forum is worth joining, although it seems to be heavy with big spenders.

 

[Roen]

https://audiophilestyle.com/forums/topic/31119-power-supply-8-group-test-lps-and-smps/

This one?

 

[graz_lag]

This gentleman in Denmark does a great job in testing batteries, USB PSU / chargers and stuffs like that ...
https://lygte-info.dk

 

[Roen]

That's a lot of information to digest, any summarized notes?

 

[graz_lag]

... Nearly all of these 5V battery packs use switching power supplies, so I don't see any likely improvement in SQ, and never heard one with mine ...

SPSU ? I am not sure I understand your point ... Once the pack is fully charged it last for days, once discharged I take it thru the recharging process overnight, the SPSU does not interfere with power supply process from the pack to the DAC ...

 

[graz_lag]

That's a lot of information to digest, any summarized notes?

He may appear here & there on different forums sometime, I have dropped him a couple of questions by email getting always good answers when I was looking to get infos on specific items ... For example the pros & cons of using 5V battery packs to power USB DACs ...