Wolf's Measurements of SMSL M400 DAC

[ReaderZ]

Hmm. Yes agree m400 is not a good match with A90. Impedance mismatch resulting in significant lack of Bass and overall punch.
*Volume compromised, for example using D90 and several other DACs with A90 with DAC all set at max output; resulted in my listening volume sitting roughly around quarter dial on A90;
* M400 requiring A90 at half dial to see same volume and "maintaining afromentioned symptoms" although all throughout there was no apparent audiable impact in dynamics. M400 is an amazing! DAC when paired with an amp that can handle its huge output impedance; just not with A90.

Not surprised as the designer JohnYang already told us that, no reason for him to mislead us as designer of A90.

 

[Veri]

Not surprised as the designer JohnYang already told us that, no reason for him to mislead us as designer of A90.

He also said that the increased voltage should make the output impedance a moot point, in theory. I would not have expected any problems tbh. Then again "bass punch" seems like something subjective.

 

[ReaderZ]

He also said that the increased voltage should make the output impedance a moot point, in theory. I would not have expected any problems tbh. Then again "bass punch" seems like something subjective.

Voltage is simply higher output to offset lower efficiency, which in James B Lansing's test shown it's not quite enough. As for less bass punch, I wouldn't know, could be subjective or could high impedance cause change in bass response the same way with headphone? I don't know if A90's(or headphone amp in general) input impedence is flat or not.

 

[solderdude]

Yes agree m400 is not a good match with A90. Impedance mismatch resulting in significant lack of Bass and overall punch.

There is no impedance matching issue at all with the A90, not at its input nor at its output. There is no impedance matching at all in audio signals to begin with.
It looks like a gain issue (as @ReaderZ mentioned).

 

[Tks]

Hmm. Yes agree m400 is not a good match with A90. Impedance mismatch resulting in significant lack of Bass and overall punch.
*Volume compromised, for example using D90 and several other DACs with A90 with DAC all set at max output; resulted in my listening volume sitting roughly around quarter dial on A90;
* M400 requiring A90 at half dial to see same volume and "maintaining afromentioned symptoms" although all throughout there was no apparent audiable impact in dynamics. M400 is an amazing! DAC when paired with an amp that can handle its huge output impedance; just not with A90.

I should probably actively seek out high impedance DACs from now on, seeing as how I can barely turn the pot on my 789 without blowing my ears to pieces using other DACs at full power.

 

[JohnYang1997]

No such thing as frequency response change. If any it will be high frequency roll off. But at these relatively low resistance, it's still not possible to affect audible range.
There's another dc block stage in M400 but I doubt that will do anything either.
As for paring with A90. The voltage will drop from 5.3V to 3.5V still close enough to 4V. Only 1db down from 4V.

 

[Veri]

Only 1db down from 4V.

I suppose comparing with a 4V DAC will therefore be more difficult. No wonder people "hear differences"

 

[ReaderZ]

I suppose comparing with a 4V DAC will therefore be more difficult. No wonder people "hear differences"

As we can see in review here, many other DAC can also output more than 4V, so the difference would be bigger than 1db and even more noticeable.

 

[themystical]

No such thing as frequency response change. If any it will be high frequency roll off. But at these relatively low resistance, it's still not possible to affect audible range.
There's another dc block stage in M400 but I doubt that will do anything either.
As for paring with A90. The voltage will drop from 5.3V to 3.5V still close enough to 4V. Only 1db down from 4V.

@JohnYang1997 What is the input impedance of the A90 in balanced mode?

 

[ShiZo]

I'm kinda confused about the thd+n vs frequency graph

 

[ChrisUK]

I was about to purchase this dac but noticed this review over at Amazon Japan, it states there is a problem with the RCA output, can Wolf confirm this?

 

[JohnYang1997]

Can confirm this

XLR above RCA with different filters.

Interesting (two set violin reference)

 

[ChrisUK]

So this DAC is useless for RCA output? Maybe firmware can fix this?

 

[Veri]

So this DAC is useless for RCA output? Maybe firmware can fix this?

Considering the XLR is correct on the same firmware, it is almost guaranteed to be something in hardware.

 

[ChrisUK]

Has a similar RCA test been done on the M500 and Sabaj D5, as these look my options now?

 

[JohnYang1997]

So this DAC is useless for RCA output? Maybe firmware can fix this?

To my knowledge, it's impossible to fix in firmware. It's the physical filter in the differential amplifier that does this.
A guess, smsl became their own victim of the high output impedance of the XLR output. Just a guess.

 

[ChrisUK]

To my knowledge, it's impossible to fix in firmware. It's the physical filter in the differential amplifier that does this.
A guess, smsl became their own victim of the high output impedance of the XLR output. Just a guess.

Was the XLR disconnected when the RCA measurement was made?

 

[Veri]

A guess, smsl became their own victim of the high output impedance of the XLR output. Just a guess.

Was thinking the same. it's the only logical explanation. On the other hand.. you get a big, fat NOS-like roll-off "for free" heh.

 

[misterdog]

I was about to purchase this dac but noticed this review over at Amazon Japan, it states there is a problem with the RCA output, can Wolf confirm this?

View attachment 73568

You did well to find this on Amazon Japan, considering it was posted on June 12th though for @JohnYang1997 to post verification plots 14 minutes after your post was even more impressive given that the time stamp on his plots are dated today.

Can confirm thisView attachment 73571View attachment 73570
XLR above RCA with different filters.

Interesting (two set violin reference)

 

[Toku]

I was about to purchase this dac but noticed this review over at Amazon Japan, it states there is a problem with the RCA output, can Wolf confirm this?

View attachment 73568

Why is the vertical scale of the graph set to SPL?