SMSL SU-9 Ultra Review featured image
Copyright SMSL 2023

SMSL SU-9 Ultra Review

Today, we review the SMSL SU-9 Ultra, which is a new BT and AK4191 + AK4499EX equipped desktop DAC capable of up to DSD512 and LDAC. It is priced at $499.99.

Disclaimer: This sample was sent to us for our honest opinion. Headfonics is an independent website with no affiliate links or partnerships. We thank Shenzhen Audio and SMSL for their support.

Click here to learn more about SMSL products that we have previously featured on Headfonics.

Note, that this article follows our latest scoring guidelines which you can find in more detail here.

SMSL SU-9 Ultra Review featured image
SMSL SU-9 Ultra Review
After giving it a thorough listen, the SMSL SU-9 Ultra proved the move to a new DAC chip manufacturer is worth the risk. SMSL flooded this diminutive DAC with enough individuality to set it apart from a sea of options out there.
Slide here to add your score on the gear!71 Votes
Most up to date AKM chip combo.
Improved design.
Synergy with most pairings is good.
Lack of airiness affects stage and realism.
The treble is a bit forceful and thin.
Reader's Score

It hasn’t even been a full year for me since the SU-9 Pro landed for review and here we are again with another desktop DAC from the same line joining the stack.

But as one of the most iterated upon platforms of SMSL, I can’t deny that the value of these sub-$500 decoders is a blessing to those ready to take a bite into higher quality audio.

Those keeping track of SMSL’s DAC products would also notice that the Chinese manufacturer is slowly mixing AKM-run devices back into their assembly line.

I think the D-6 which I reviewed last year was the first AKM DAC they did after the long hiatus. The C100, which is an ultra-affordable entry-level DAC SMSL released in the earlier part of the year was also powered by an AKM chip.

Both cases mentioned above don’t share the strong following and built identity of the SU-9 line. What I mean is that the past three generations of SU-9 DACs all used ESS chips.

And so, when I read the banner of the SU-9 Ultra and saw AKM in big and bold letters, it raised a flag in my mind that this could be momentous for SMSL if done right, or the other way if not.

SMSL SU-9 Ultra Technical Features
Copyright SMSL 2023

Tech Highlights

The SU-9 Ultra is the first desktop DAC in the series to use the latest AKM AK4191 and AK4499EX chipset duo combined with Bluetooth 5.0 wireless connectivity. It is capable of decoding up to PCM 32Bit/768kHz and DSD512 natively with MQA and MQA-CD support still available

I don’t know how many DACs out there are already using this new chip design of AKM since I personally only encountered it once before with the Gustard A26.

Breaking down the process of digital to analog conversion into a two-fold set of specialized discrete components, the AK4191 is created to act as the digital filter and delta-sigma modulator, which then feeds to the AK4499EX for the main decoding.

I have to admit that having two distinct chips compared to one, and the fact that it is the same kind the A26 uses, has a psychological effect of the SU-9 Ultra being more sophisticated than it is.

But aside from this fact, nothing else really changed. I’m hesitant to call the SU-9 Ultra a replacement for the SU-9 Pro since the two have so many similarities except for their DAC chip supplier.

If SMSL continues to sell the SU-9 Pro at the same price as the SU-9 Ultra, then you can assume SMSL left the decision to the consumer.

SMSL SU-9 Ultra design


For some bizarre reason, ‘SMSL SU-9’ is what’s printed on the front of the chassis. Only after I rotated to the rear of the unit and read the ‘SU-9 Ultra’ scripted on one corner was I able to discern this unit as being the latest as opposed to the original.

If it’s not obvious why I started with this lighthearted reflection, well it’s because there’s not much else to see here pointing out that the SU-9 series has been out for a while.

With a now familiar aluminum chassis build and dimensions that are very much the same as the SU-9 Pro, the SU-9 Ultra maintains a petite 0.79kg weight.

Naming it ‘Ultra’ though is still not a good enough excuse for SMSL to make the feet even numbered. So yes, there are three low-profile in a triangular configuration as opposed to a steadier 4 supporting feet underneath just like with every SU-9 released.

SMSL SU-9 Ultra rear panel


The rear of the SU-9 Ultra is similar to the SU-9 Pro save for one change, the USB input, which is now upgraded to the more modern USB-C socket. A cable is provided inside the box, so don’t worry if you still don’t have one lying around.

To flex its full MQA decoder capabilities, the SU-9 Ultra can be fed via USB, optical, or coaxial. Its Bluetooth antenna is version 5.0 and can decode most modern codecs including LDAC.

Spec chasers will notice the slight drop in dynamic range on both the XLR and RCA outputs of the SU-9 Ultra compared to the Pro. The 2.5Vrms of the RCA port remains unchanged though, while on the XLR, it is now evened out at 5Vrms instead of the 5.2Vrms of the Pro.


Much like the SU-9 Pro version, and the SU-10, the SU-9 Ultra boots up to active status when you first plug it into the wall rather than switch to standby. I only note this since I always leave the house with unused appliances unplugged.

The full-color display when turned on only brings forth the essentials while tucking away the more complex set of settings in a separate sub-menu to keep things tidy. Aside from easily reading the currently selected input in the upper left corner, the volume level is centrally presented as well for daily use.

Volume attenuation increments at 0.5dB intervals on every turn of the wheel or press of the remote. Using the rotary knob on the unit itself is still the faster way for sweeping the full range of volume from one end to the other.

Upping the user experience since I first tried it on the SU-10, the easy-to-understand interface of the SU-9 Ultra makes having a display meaningful. Now that there is an AKM chip inside, most settings are still available, but the choices for each are not parallel anymore to when an ESS chip was used.

SMSL SU-9 Ultra accessories

Packaging & Accessories

The SU-9 series has always used a black sleeve with a bleached belt to print the current model unlike the other gears I receive from the SMSL where you’ll only get a plain box and that’s it.

While nothing out of the ordinary changed on the SU-9 Ultra, I think the company thinks highly of this line.

Opening the box, the user manual was unusually made present immediately even before I could remove the topmost foam layer. Aside from this observation, SMSL also changed it into a square booklet kind which looked neater coming from the old folded leaflet style.

Then there’s the usual stuff. The SU-9 Ultra is wrapped in plastic and nestled safely on the left. All the accessories are also carried over from the SU-9 Pro except for the USB cable which is now in type C to couple with the USB-C input on the rear of the unit.

Sound Impressions

The following sound impressions were created using the SMSL SU-9 Ultra connected to SMSL’s H300 headphone amplifier and the Audio Technica ATH-ADX5000 headphones.


‘Wow’ is what came to mind when I ran the SU-9 Ultra for the first time. That’s on top of my awareness of the fantastic value the SU-9 Pro provides when I reviewed it earlier this year. Be sure to read my page 2 comparisons for a deeper dive into the differences between the two.

Stressing the knocking beat of synths, the SU-9 Ultra tilts the sway to be perceptible enough but not too bold. It is shy of warmth, making sure each beat is clear and diffused with vividness. Here, bass guitars reverberate in soft doses with the casual timbre decreasing the strength of each bite.

I also really like the midrange since the refined silkiness of the SU-9 Ultra is entwining the sound with reminds me of the Gustard A26. The key here is control and SMSL surely isn’t hiding the AKM it has stuck inside.

The subtleties and air of voices could still use more effort however since certain songs are sacrificing some of the vocal range and texture. This doesn’t mean the SU-9 Ultra is not detailed since I can still reliably expect breathier parts to come up when I listen a little closer.

Making me lean back a bit on my excitement with the SU-9 Ultra is the treble range noting the raw response it gave to instruments such as electric guitars and horns. While it is more on point with texture, it is at the expense of sounding thin and vigorous.

SMSL SU-9 Ultra paired with HarmonicDyne Zeus Elite

Staging & Dynamics

The biggest contributing factor limiting the soundstage of the SU-9 Ultra for me is its lack of airiness. This is not the case for the SU-9 Pro so the change in DAC manufacturer surprisingly did divide the presentation of the two.

Subtleties and whispery sections do add some sense of space but it will never reach the floating effect of the SU-9 Pro. Having the resolution and image separation to defend itself, it leans to its exquisite midrange flavor as an additional weapon to hypnotize within the bounds of its honest stage.

Click on page 2 below for our recommended pairings and selected comparisons.

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