SMSL SU-6 Review (Desktop DAC)

[Jerderv]

I ordered mine, just cleared customs at LAX! I'll be using this to run a 2.1 setup in my living room for 50/50 movies/music. It is replacing an SMLS Q5 Pro. I plan on using the optical connection from the TV to the SMSL SU-6. I'm planning on using the SU-6 for volume control. I'll run RCAs from the SU-6 to my MiniDSP 2x4 where I'll set the crossover and apply room correction. From the MiniDSP I'll run RCAs to my crown XLS1502 powering a pair of Dayton B652 Airs(for now), and to my Crown XLS2502 to power my Stereo Integrity HT18 v.3 subwoofer. Im new to this stuff, im open to suggestions and I have a couple questions.

• Is optical the ideal connection method from TV to the SU-6?
• Does the light link quality have a large impact on audio quality?
• The SU-6 Appears to have 2v output, my miniDSP 2x4 is currently configured for a 0.9v input/output. Is it best to reconfigure the DSP for 2v input while the output remains at 0.9v?
• SU-6 DPLL setting: The manual states, "When the clock stability of the input signal is not good, the sound may be interrupted. Increase this value can avoid the sound interruption! Especially when using TV as signal source!" DPLL is adjustable 1 through 9. Im not an experienced critical listener, would it be best for me to just set the DPLL to 9 and not look back, or would this setting be worth trying to find a minimum without sound loss?

Thank you for any input!

 

[pwn87]

• Is optical the ideal connection method from TV to the SU-6?

yes,
bluetooth can have pairing and connectivity issues depending on the situation (might not apply for you)
usb (from a pc) will be noisy if the dac & sources volume is not set close to max level (for this you should set amplifier volume only as high as necessary for the worst case ... or control the volume over the amplifier)

• Does the light link quality have a large impact on audio quality?

none (its a digital connection)

• The SU-6 Appears to have 2v output, my miniDSP 2x4 is currently configured for a 0.9v input/output. Is it best to reconfigure the DSP for 2v input while the output remains at 0.9v?

no idea, someone else answer this please

• SU-6 DPLL setting: The manual states, "When the clock stability of the input signal is not good, the sound may be interrupted. Increase this value can avoid the sound interruption! Especially when using TV as signal source!" DPLL is adjustable 1 through 9. Im not an experienced critical listener, would it be best for me to just set the DPLL to 9 and not look back, or would this setting be worth trying to find a minimum without sound loss?

it's probably worth starting out at 1 and only increase it if you notice any audio issues, i've read these new dacs can handle a lower dpll setting with the same source hardware, anyway i didn't have any problems at 1 so far

 

[Acerun]

Wow, this looks like my next desktop DAC. Excellent sound, internal power supply, a display showing the current rate, and a correct filter at 44 kHz that is flat at 20 kHz and fully attenuated at Nyquist.

Might I ask what you mean by this, sorry I don't quite understand. Which "correct filter" are you referring to and what does fully attenuated at Nyquist mean. I just got mine and have it set to DPLL 1 and PCM FL 3 per another member's suggestion. Thanks.

 

[Acerun]

Does the BT have ldac?

Yes it does

 

[Vini darko]

Might I ask what you mean by this, sorry I don't quite understand. Which "correct filter" are you referring to and what does fully attenuated at Nyquist mean. I just got mine and have it set to DPLL 1 and PCM FL 3 per another member's suggestion. Thanks.

It means full frequency attenuation by half the sample rate without compromising the audible band.

There are two filters wich achive this 2 and 3. 1 rolls off early cutting 20khz by nearly 10db. If you want to learn more about it look up nyquist therom for digital audio.

 

[MRC01]

It means full frequency attenuation by half the sample rate without compromising the audible band.
...
There are two filters wich achive this 2 and 3. 1 rolls off early cutting 20khz by nearly 10db. If you want to learn more about it look up nyquist therom for digital audio.

Yes that's what I meant. But really only 1 correct filter, because 2 (maroon) also rolls off a bit early, about -3 dB at 20 kHz.
Filter #3 (cyan) is the only one that is fully attenuated by 22.05 kHz with no passband attenuation.
Few DACs have such a correct filter. Most have either (A) some passband attenuation, or (B) don't fully attenuate until 24.1 kHz. The reason is that 44.1 k sampling has such a narrow transition band, it's hard to implement a correct filter that operates in real time and runs within the processing constraints of a typical DAC chip.

 

[MRC01]

• Is optical the ideal connection method from TV to the SU-6?
• Does the light link quality have a large impact on audio quality?

Bluetooth is the worst way to connect it because the codecs are all lossy. USB, coax and toslink (optical) are equivalent in terms of delivering the exact same bits. Toslink has the advantage of electrical isolation (no metallic contact between the devices) which can prevent ground loop hum. Yet it has the disadvantage of maxing out at 96 kHz sampling. For higher sample rates, or DSD, you need coax or USB.

• SU-6 DPLL setting: The manual states, "When the clock stability of the input signal is not good, the sound may be interrupted. Increase this value can avoid the sound interruption! Especially when using TV as signal source!" DPLL is adjustable 1 through 9. Im not an experienced critical listener, would it be best for me to just set the DPLL to 9 and not look back, or would this setting be worth trying to find a minimum without sound loss?

It sounds like the DPLL setting determines how much the SU-6 buffers the input signal. If so, higher lower values may be more stable, less jitter (as Amir measured in the review!) and the only drawback is that it will take longer to sync or adapt if the input bit rate changes. I would leave it on the highest lowest setting, as the bit rate never actually changes mid-song or mid-movie, so who cares if it takes a few seconds to adapt when you change albums?

 

[Acerun]

Bluetooth is the worst way to connect it because the codecs are all lossy. USB, coax and toslink (optical) are equivalent in terms of delivering the exact same bits. Toslink has the advantage of electrical isolation (no metallic contact between the devices) which can prevent ground loop hum. Yet it has the disadvantage of maxing out at 96 kHz sampling. For higher sample rates, or DSD, you need coax or USB.

It sounds like the DPLL setting determines how much the SU-6 buffers the input signal. If so, higher lower values may be more stable, less jitter (as Amir measured in the review!) and the only drawback is that it will take longer to sync or adapt if the input bit rate changes. I would leave it on the highest lowest setting, as the bit rate never actually changes mid-song or mid-movie, so who cares if it takes a few seconds to adapt when you change albums?

Interesting, yes, I have noticed that it misses the first couple seconds of a song when I start a new album.

 

[Jimster480]

As this has digital in, a power cable is a good choice to go with other devices (TV, smart devices, etc). However, for desktop use, there should be an additional option for USB power IMO.

I agree, it would be cool if it COULD BE powered by USB-C if you have the machine for it.
Otherwise it looks to be pretty amazing for only $169.

 

[MRC01]

Interesting, yes, I have noticed that it misses the first couple seconds of a song when I start a new album.

That's surprising; I expected it would add latency rather than chop off the music.

 

[Zek]

Can anyone show a display when playing PCM and DSD files.
Thanks in advance.

 

[Acerun]

That's surprising; I expected it would add latency rather than chop off the music.

I believe I was using Bluetooth at the time so maybe that exacerbated the issue

 

[Acerun]

So my Pixel 6 is not recognizing the SU-6 via USB C to USB C cable. My Pixel 6 recognizes the RME ADI-2 FS just fine via USB C to USB B... Any ideas? Are some USB-C to USB-C cables for data only and won't carry an audio signal or might there be an issue with the SU-6?

 

[Acerun]

So my Pixel 6 is not recognizing the SU-6 via USB C to USB C cable. My Pixel 6 recognizes the RME ADI-2 FS just fine via USB C to USB B... Any ideas? Are some USB-C to USB-C cables for data only and won't carry an audio signal or might there be an issue with the SU-6?

Might this be a legitimate reason? https://www.reviewgeek.com/105739/googles-pixel-6-is-disappointing-audiophiles-heres-why/

 

[madDog]

Looking for a dac so i could connect my powered monitors to my tv via optical and PC. Is this the best option under 200$ ? Also looking at topping e30. Any other alternatives out there guys ? So much stuff out there that measures well, its getting hard to pick the right one.

 

[Acerun]

Looking for a dac so i could connect my powered monitors to my tv via optical and PC. Is this the best option under 200$ ? Also looking at topping e30. Any other alternatives out there guys ? So much stuff out there that measures well, its getting hard to pick the right one.

The SU-6 is the one I chose. So small, bluetooth with LDAC, measures and sounds great. It's so small I mounted it in the garage w velcro.

 

[madDog]

The SU-6 is the one I chose. So small, bluetooth with LDAC, measures and sounds great. It's so small I mounted it in the garage w velcro.

Tnx for the reply buddy. Will either go with su-6 or maybe dx3pro+ so i also have a good headphone amp on standby.

 

[kanjerkoe]

The SU-6 is the one I chose. So small, bluetooth with LDAC, measures and sounds great. It's so small I mounted it in the garage w velcro.

Hey Acerun, I have been eyeing the SU-6 myself. My usecase will be hooking it up to my existing hifi equipment for the bluetooth connection. How are you enjoying the sound quality you get by using the SU-6 with LDAC?

 

[Acerun]

Hey Acerun, I have been eyeing the SU-6 myself. My usecase will be hooking it up to my existing hifi equipment for the bluetooth connection. How are you enjoying the sound quality you get by using the SU-6 with LDAC?

I'm no expert, but I think it sounds really good. Love LDAC for bluetooth.

 

[Jerderv]

Got mine! Running FL3 and DP1. Setup is a SU6 to miniDSP to a Crown XLS1502 driving a pair of dayton audio B652 airs and to a Crown XLS2502 bridged driving a single Stereo integrity HT18 v.3. It gets very loud. So far im thrilled with the sound quality. I cant wait to replace the Daytons with something better. I still have plenty of more tweaking to do, im very new to REW, im having tons of fun.

Side note, I used REW on my laptop to generate a 1000hz tone hooked to the TV via HDMI and then optical to the SU6. I turned the volume up on the SU6 and monitored the miniDSP input gain. Surprisingly -0db on the SU6 is right at -0.5db on the miniDSP when configured to the .9v input sensitivity. I also searched for and played some "0db" tracks from youtube and spotify they also put the miniDSP at -0.5db. I guess the SU6 does .9v output at 0db?

EDIT: there is significant distortion/clipping above -10 when ran through the mini dsp. If I run the rca out directly do the xls1502 when in 1.4v sensitivity mode there is no aduiable clipping/distortion.

EDIT 2: Changed the input sensitivity on the minidsp to 2v. Much better! SU6 at 0db is about -1.5db on the minidsp. No clipping.

Still a work in progress.