SMSL SU-9 Balanced DAC Review

[Trell]

Long story short: no benefit in having a preamp, digital volume is as good as analogue. But PLEASE make sure the maximum output voltage of your DAC (I guess SU-9 has 4 or 5 volts with xlr out) does not put in clipping your amplifier. An amplifier in clipping can seriously damage your speakers. If this risk is possible, then check this post https://www.audiosciencereview.com/forum/index.php?threads/topping-d70s-fried-my-speakers.38706/ unfortunately chi-fi dacs can have buggish software that can randomly reset the volume to the max. In my case the topping D70S had a max voltage of 5v while my amplifier (Audiophonics Purifi) was designed to clip at 4v. The dac unpredictably set the volume to the max and my speakers got fried...

For protection passive attenuators are very useful, not only for the speakers but also the hearing.

Here is a thread on the RME user forum discussing this along with examples of passive attenuators for balanced as well as unbalanced.

Level mismatch solutions - fixed and variable attenuators (Page 1) — Tips & Tricks — RME User Forum

Level mismatch solutions - fixed and variable attenuators (Page 1) — Tips & Tricks — RME User Forum —

forum.rme-audio.de

 

[JSmith]

buggish software that can randomly reset the volume to the max.

Not while the unit is in operation though... only when powered down and powered up at another time. One should always turn on the DAC first, check the volume level and then turn on the amp. Terribly sorry though to hear your speakers were damaged in this case, how frustrating.


JSmith

 

[MeZoX]

OP should update the review to include the distortion issue with early releases , as done with the M500

I just got an SMSL SU-9 myself today based on the recommendation from the review, only to figure out later on when reading more into this thread that it has the distortion problem lol

 

[Roland68]

Not while the unit is in operation though... only when powered down and powered up at another time. One should always turn on the DAC first, check the volume level and then turn on the amp. Terribly sorry though to hear your speakers were damaged in this case, how frustrating.


JSmith

Unfortunately, most users are unteachable on this point and (do not want to) understand the actual problem.
When the volume control in a DAC uses the digital volume reduction (please mind my choice of words) of the DAC chip, there is always a potential hazard.
The physical starting point of the DAC chip is to convert 100% of the digital data into analog, that is its basic task.
If the volume is to be reduced, the digital data must first be reduced and this must be actively controlled via the software.

It should be clear to everyone that there is no such thing as a perfect device and that the initial state, no matter why an error may occur, is always 100% digital data = 100% volume.
That's why I would never connect my power amplifiers to a DAC without an additional volume control.

 

[marcom22]

Unfortunately, most users are unteachable on this point and (do not want to) understand the actual problem.
When the volume control in a DAC uses the digital volume reduction (please mind my choice of words) of the DAC chip, there is always a potential hazard.
The physical starting point of the DAC chip is to convert 100% of the digital data into analog, that is its basic task.
If the volume is to be reduced, the digital data must first be reduced and this must be actively controlled via the software.

It should be clear to everyone that there is no such thing as a perfect device and that the initial state, no matter why an error may occur, is always 100% digital data = 100% volume.
That's why I would never connect my power amplifiers to a DAC without an additional volume control.

For you and for your mind. I never had problem with DAC volume control from topping to Smsl. Regards

 

[Celty]

For you and for your mind. I never had problem with DAC volume control from topping to Smsl. Regards

No problems for me either.

 

[Roland68]

For you and for your mind. I never had problem with DAC volume control from topping to Smsl. Regards

Just like many others here.
Then suddenly the tweeters burned out (or more) and of course the manufacturer, software, etc. are to blame, but of course never the user, there are already a few threads about it here.
I don't care, it's not my money and my speakers that get scrapped...

 

[MeZoX]

anyway to know if this is in need to update firmware ? just got it this week

 

[Roland68]

anyway to know if this is in need to update firmware ? just got it this week

As far as I know, you cannot update the firmware on the SU-9 yourself. In Europe, the devices had to be sent to Audiophonics at the time.
I seem to remember that the changed firmware could only be recognized by a sticker, since SMSL had not given the new firmware version a new "number".

 

[marcom22]

As far as I know, you cannot update the firmware on the SU-9 yourself. In Europe, the devices had to be sent to Audiophonics at the time.
I seem to remember that the changed firmware could only be recognized by a sticker, since SMSL had not given the new firmware version a new "number".

Correct

 

[MeZoX]

sending it back will be a very expensive process for me ,is there a way to check if it needs to be sent back in the first place ?

 

[Roland68]

sending it back will be a very expensive process for me ,is there a way to check if it needs to be sent back in the first place ?

According to the serial number and the position (side, not bottom), you have the current version.
But since SMSL dealt with the problem in an absolutely unprofessional way, no visible change in the firmware version, no reliable marking, only unprofessional and incorrect information (own experience), probably not even an employee can give you reliable information without flashing the device again.

Therefore, after 3 attempts to get a current device, I simply bought something else.

 

[Vapor9]

Unfortunately, most users are unteachable on this point and (do not want to) understand the actual problem.
When the volume control in a DAC uses the digital volume reduction (please mind my choice of words) of the DAC chip, there is always a potential hazard.
The physical starting point of the DAC chip is to convert 100% of the digital data into analog, that is its basic task.
If the volume is to be reduced, the digital data must first be reduced and this must be actively controlled via the software.

It should be clear to everyone that there is no such thing as a perfect device and that the initial state, no matter why an error may occur, is always 100% digital data = 100% volume.
That's why I would never connect my power amplifiers to a DAC without an additional volume control.

This must be the reason I find the sound of a DAC inferior to having a preamp in the loop. It's usually argued that a preamp is unnecessary with today's DACs, but that is certainly not my experience.

 

[norcalscott]

anyway to know if this is in need to update firmware ? just got it this week

I'm pretty sure that is the latest, as if I remember correctly (I can't locate the original post on this) - there was a misspelling in the original firmware. When SMSL did an update, they (for some crazy reason) did not increment the version number, but did fix the misspelling. I went through all this a while back when I got my SU-9.

By the way, FWIW - I have been using mine as a preamp with an SMSL AO200 amp, which I have set at max volume (70) and I have never experienced any distortion or quirks in the SU-9 - it has been rock solid and I am very happy with it. It is dead silent in my system with volume of the SU-9 at 0.

 

[MeZoX]

I'm pretty sure that is the latest, as if I remember correctly (I can't locate the original post on this) - there was a misspelling in the original firmware. When SMSL did an update, they (for some crazy reason) did not increment the version number, but did fix the misspelling. I went through all this a while back when I got my SU-9.

By the way, FWIW - I have been using mine as a preamp with an SMSL AO200 amp, which I have set at max volume (70) and I have never experienced any distortion or quirks in the SU-9 - it has been rock solid and I am very happy with it. It is dead silent in my system with volume of the SU-9 at 0.

honestly I don't believe the issue is audible even at 100% volume , Anyways I have the DAC connected to a 2.1 setup intended for nearfield listening at my pc , with two 8" studio monitors I barely even let the sound go over 30% and anything over that I will be damaging to my hearing , I got it at a good sale for 140 USD so I am quite glad overall , although I have a superior performing DAC (on paper) the Topping E50 , I prefer the feature set of the SU 9 and also the presence of a volume Knob makes it much more ergonomic for my use case , other than that i cant tell any difference between them acoustically by ear

 

[Lew3vans]

I found this currently on offer in the uk for £275!!! Absolute bargain….. So I bought one to go with my SH-9

https://amzn.eu/d/f3nap7l

 

[mrjayviper]

can someone please explain the distortion problem? I found a local seller for this device at a good price. thanks

 

[mrjayviper]

Anyone? Thanks a lot!

 

[mycose]

Anyone? Thanks a lot!

Here's more information about it:

strange SMSL M500 high 3rd harmonic

I just got a brand new SMSL M500. it's the latest 1.7 firmware and 1.3 hardware version. (windows shows 2.06 in xmos utility). The following measurements are done with computer -> USB-> M500 XLR output-> ADI-2 Pro input -> computer. I use REW to generate the sine wave and plot the fft. If I...

www.audiosciencereview.com

TL;DR: if both channels don't play the same audio signal, the output will have some harmonic distortion.

Chances are you won't hear this at all, but you're paying >$300 for a product that should NOT have this kind of issues.

 

[norcalscott]

FYI - I read through that M500 thread again and found what I was trying to remember for seeing if the SU-9 has the latest firmware - I cannot vouch for this, but one poster noticed that the “new” firmware, with the fix, did not have 2020 in the “ 2020 SMSL” part under the firmware numbers (is just “SMSL”). I had purchased my SU-9 in Feb 2022 and my firmware screen does not have the 2020 in it, so it seems reasonable that this information is correct.

Edit - here is a link to the post, which includes a screen shot:
Post in thread 'strange SMSL M500 high 3rd harmonic'
https://audiosciencereview.com/foru...msl-m500-high-3rd-harmonic.22710/post-1010462