SMSL M500 DAC and HP Amp Review

[m8o]

Nice form factor, feature set, and performance. I'd buy one.

Surprised to see the relatively high 5th, 9th, and other harmonics above and below that. Yes, I know they are super low in level. But still unusually high relative to the 2nd, 3rd & 4th. Not something usually seen in the highest performing devices.

 

[617]

Am I missing something or is a 7V output excessively strong? I'm looking for a DAC with a volume control which I can run into an IcePower amp I'm building, but the max input level for the amp is 3V. Is this a problem? Should I look for a DAC with a ~2V output?

 

[Jimster480]

Am I missing something or is a 7V output excessively strong? I'm looking for a DAC with a volume control which I can run into an IcePower amp I'm building, but the max input level for the amp is 3V. Is this a problem? Should I look for a DAC with a ~2V output?

2v output would be with RCA only. Typically 4V is standard for XLR.
You can turn the level down with this DAC as amir has shown.

 

[mi-fu]

M500 seems to have 40-step digital volume control. Is it enough for the near 7V output?

 

[amirm]

M500 seems to have 40-step digital volume control. Is it enough for the near 7V output?

Yes. To get roughly 4 volt, you operate it at 34 volume level so you have all of that to play with.

 

[617]

Yes. To get roughly 4 volt, you operate it at 34 volume level so you have all of that to play with.

Is that 34/100 or 34/40 steps?

Would it make sense to make some kind of inline attenuator? 7v just seems quite strong.

 

[dkinric]

Yes. To get roughly 4 volt, you operate it at 34 volume level so you have all of that to play with.

I'm curious too as to how this will affect use as a pre-amp, going directly to an amp without gain controls. Amir, 34 out of how many (what is max volume setting ie 34/100)? It would be a factor for me if there were not enough steps to make slight volume adjustments.

 

[lastexile]

34 out of 40 and 40 is max volume. I've only used UBS in and RCA outs to my JDS LABS ATOM so far. I did notice I didn't have to turn the volume up nearly as high on the ATOM from the SU-8

 

[stunta]

Thanks for the review Amir. Its great to see high quality DACs at lower price points.

Are the XLR and RCA outputs both active at the same time?

 

[ryohnosuke]

Are the XLR and RCA outputs both active at the same time?

YES

 

[Tizziano]

@amirm how do you do with headphones with 150 ohms? For example about HD700.

 

[nscrivener]

Would it make sense to make some kind of inline attenuator? 7v just seems quite strong.

Yes. Attenuators are cheap and unlike potentiometers shouldn't degrade the sound quality. This also has the advantage of maximising your SNR, as analog attenuation will reduce both the signal and the noise from the dac, whereas adjusting the volume digitally will reduce the signal but the noise will remain constant. If the noise from the dac is below the audible threshold anyway this won't make a difference.

 

[m8o]

And it comes in RED!

 

[amirm]

@amirm how do you do with headphones with 150 ohms? For example about HD700.

Just multiply the power ratings for 300 ohm by two.

 

[Mnyb]

How is that generalization? The dac1421 has horrible measurements. Are you kidding me!?? This dac is in the red and you going to justify that is your rebuttal to me?

Jeez man....

Back to my non-generalization answer. R2R dacs are the devil.

It’s 20dB better than the horror show that is the arist ! ( dB is logarithmic so it’s a lot ) they are even better R2R out there.
Not as good as a chip DAC thou

 

[Kane1972]

Yes. Attenuators are cheap and unlike potentiometers shouldn't degrade the sound quality. This also has the advantage of maximising your SNR, as analog attenuation will reduce both the signal and the noise from the dac, whereas adjusting the volume digitally will reduce the signal but the noise will remain constant. If the noise from the dac is below the audible threshold anyway this won't make a difference.

Any recommendations for an attenuator?

 

[Kane1972]

I already have an M Patch 2, is this good enough?

 

[TC!!]

Any recommendations for an attenuator?

My main concern with the M500 is also the output level, this seems to be an extra cost and for me starts pushing the price closer to the Sabaj D5.

Actually this sounds like another thing @amirm could measure which could be useful for this community to understand, just like his measurements on devices which 'clean' the USB signal. It'd be very useful to see if there is any difference between an analogue attenuator and the digital volume control of the device.

 

[sonci]

I don't see why hot output is a problem for the M500, I recall the Benchmark dac was even louder..

 

[TC!!]

I don't see why hot output is a problem for the M500, I recall the Benchmark dac was even louder..

You're absolutely right, here's the review of the Benchmark DAC3. In that review Amir had to use a pad inside the device to bring the level down by 10dB, from 20v to 13v, which brought it in line with the RME ADI 2 which also seems to be capable of a higher than 'normal' voltage output.
Amir doesn't show the output voltage of the RME in its own review but says this in the review where he compares the Pro version:

Note: the ADI-2 Pro was running at +19 dBu which produced the correct 6.9 volt output. The ADI-2 DAC however, was run at +13 dBu which produces slightly lower output at around 6.8 volt (from memory) which is incorrect. Maybe it needs a firmware update. Regardless, I tried matching the levels by dropping the volume by 0.5 dB on ADI-2 Pro but the results did not change.

I've looked through the manual for the RME and get the impression you can change the level of the output. I see a lot of positive feedback on the forum for the RME DAC and it's these kinds of features that put it above the cheaper Chinese DACs.

Line Output: Ref Level
Sets the reference level for the analog outputs. Choices are -5 dBu, +1 dBu, +7 dBu, +13 dBu
at the RCA output, referenced to digital full scale level (0 dBFS). The levels at the XLR output
are 6 dB higher, +1 dBu, +7 dBu, +13 dBu, +19 dBu.

Finally though in the review of the Benchmark DAC3 Amir praises the higher output voltage. As he explains room correction systems work by attenuating signals, a higher output voltage gives you more headroom for room correction systems to be used.