Headphone Ampilifers, Reviews

Review: SMSL DA-9 2-Channel Stereo Amplifier – Little Box, Big Power

In what I can only assume is an unholy mixture of black magic, witchcraft, and high-tech electronics, SMSL has redefined what I know about speaker amplifiers. Thank you to HiFiGo for…

In what I can only assume is an unholy mixture of black magic, witchcraft, and high-tech electronics, SMSL has redefined what I know about speaker amplifiers.

Thank you to HiFiGo for providing the SMSL DA-9 for review purposes.

I admit it. I’m old school (or perhaps just old). In my mind, stereos consist of several large, heavy, metal boxes connected with garden-hose-sized wires to a pair of giant wooden monoliths. A proper stereo needs about 20 square feet or so of floor space to set up correctly, and they tend to have a dominating and overwhelming presence in a room.

In fact, I’ve got several such stereos scattered over various rooms in my home that my (very understanding) family lives with. Music is very important in this household, and having full-sized shrines dedicated to audio reproduction seems par for the course.

I do quite a few headphone audio component reviews, so I’m familiar with SMSL and their feature-rich, bang-for-the-buck products. I’ve recently reviewed the excellent SU-9 DAC, so I was intrigued when offered the chance to try out the matching DA-9 stereo amplifier.

The SU-9 DAC is a small plain box with a screen and a single knob. The DA-9 uses the same form factor, and to my (ahem… old) eyes looks far more like a DAC than a stereo amp.

Where are the plethora of buttons and knobs? How is there no fan or slots for venting heat?

SMSL also offers the matching SH-9 headphone amplifier.

Despite its very unassuming looks, the DA-9 boasts a feature set typically only found on expensive components.

Oh, did I forget to mention that the DA-9 is also bargain-priced at around $250 USD? Yet it features fully-balanced topology and design from input to output, subwoofer connection, remote control, color LCD display, tone controls, EQ pre-sets, Bluetooth 5.0 (with multiple high-quality codec support), and shocking output power for a device this size (50wpc @8Ohms, 90wpc @4Ohms, 150wpc @2Ohms).

Nearfield listening is becoming ever more popular these days, so the small form factor makes sense to appeal to those with limited space. The triple stack of SU-9, SH-9, and DA-9 makes a very tempting all-in-one desktop combo. Clearly, this was firmly in mind when SMSL designed the DA-9 but is it really good enough for full-sized stereo duties?

Yes. Somehow it is. Voodoo, I tell you.

Company Overview

SMSL stands for the Foshan ShuangMuSanLin Technology Co., Ltd. Founded in 2009, SMSL is located in Shenzhen, China. They have their own R & D, manufacturing, and marketing teams and specialize in producing audio products, including DACs, stereo headphone amplifiers, speakers, and power amplifiers.

SMSL has established a comprehensive sales network, and its products are exported to more than 30 countries worldwide. SMSL states that they are “quality-based, technology-guidance, customer central.” They strictly execute the Electronics Industry rules (EICC) and have passed the CCC, BQB, MFi, CE, FCC, RoHS, CE-EMC, CE-LVD, WEEE certifications.

Technical Specifications

  • Inputs: XLR. RCA. BT
  • THD+N: 0.003%
  • SNR: 11dB
  • Channel separation: 96dB
  • Input Sensitivity/Input Impedance: 250mV/47k0
  • Output Power: 150Wx2(2Ω) / 90Wx2(4Ω)/50Wx2(8Ω)
  • Power Consumption: 40w(Normal Volume)
  • Standby Power: 0.5W
  • Dimensions:187.5X154X40mm(WxHxD)
  • Weight: 0.96kg


The DA-9’s packaging is unremarkable, with a cardboard box contained in a logoed paper sleeve. Inside, the amplifier and accessories are securely nestled in foam cut-outs.

In the box

  • DA-9 amplifier
  • Bluetooth antenna (screw-on)
  • Remote control
  • IEC power cable
  • Manual

The accessories are minimal, but that’s to be expected at this price point. Of note, the power supply is internal, so there is no wall-wart type power cable. The black plastic remote is functional but straightforward and is identical to the one included with the SU-9 and SH-9. A single remote controls all devices, switching between them by pressing the A, B, or C buttons on the remote (A for the DA-9).


The flat black aluminum case is anodized and chamfered with rounded edges. The fit and finish are excellent, and it feels great to touch. The front face couldn’t be simpler, with a bright full-color display in the center and a single multi-function, light aluminum knob on the right.

Press the knob to turn on, and press and hold to turn off. Twist the rotary controller to change volume or move between menu options. Press to select, hold to exit. It’s all entirely intuitive and simple to navigate.

The menu structure is pretty straightforward as well: Input selection, EQ presets, Bass and Treble tone controls, Soft Clipping on/off, six levels of Screen Brightness, and Version information. The EQ presets (Direct, Tone, SDB, Bass, Super Bass, Rock, Soft, Clear) are all noticeably different sounding.

The SDB EQ setting is essentially a low and a high shelf equalization that boosts bass and treble, much like a loudness control. This is pleasing for low-volume listening, but I’d suggest sticking with the Direct setting for critical listening.

The rear panel is a bit more crowded to fit analog RCA and balanced 3-pin XLR inputs, four banana-plug compatible speaker cable binding posts, Bluetooth antenna, subwoofer RCA output, and a full-sized IEC power cable socket. It all works fine, it just requires a little preplanning when plugging things in, but I highly recommend using banana plugs for speaker wires rather than screwing them down.

The subwoofer RCA output is full-range with no cut-off, output level, or high-pass filter, requiring the subwoofer to filter out unwanted frequencies.

Of note, SMSL insists that three rubber feet are sufficient for this form factor. For the most part, it’s okay but can get a bit tippy with a complete set of thick cables attached. Another adhesive rubber foot would avoid this.

A significant difference between the DA-9 and a standard stereo amplifier is the limited number of inputs. There are two switchable analog inputs (single-ended and balanced) meant to connect to an outboard DAC. However, the included Bluetooth input does mean that you can use the DA-9 without any connected component beyond your phone.

If you are creative, you could use a turntable with line-level outputs connected to the RCA jacks, or better yet, an inexpensive multi-input RCA switch box to add more flexibility.

There is a slight pop noise audible through the speakers when changing inputs.


The DA-9 is my first real introduction to quality class D amplification. And it’s here where the magic happens. Based on a pair of German Infineon class D circuits, the DA-9 boasts 92% efficient amplification, with low distortion, minimal power consumption, and virtually no heat when operating. Heck, I’m used to a 17.5wpc tube amplifier powering my living room stereo setup, so a cold-running, tiny 50wpc (@8Ohms) amplifier is bound to seem like magic.

In 1962, science fiction writer Arthur C. Clarke wrote that “any sufficiently advanced technology is indistinguishable from magic.” The DA-9 is clearly made from that advanced tech.

The multifunction knob is mated to NJRC’s NJW1194 2-channel electronic volume control with input selector and tone control. It uses a resistance ladder circuit to eliminate any channel imbalance often found with analog volume potentiometers (especially near the bottom of their range).

The internal large-frame, low-leakage, switching power supply transformer is designed to produce greater magnetic flux and more available instantaneous power than typical power supplies for improved dynamic performance. It also features two levels of main power input filtering.

When powered on, there is a slight, audible electronic whine noise audible if you are within 16 inches of the DA-9 in a quiet environment.

The Bluetooth circuitry is SMSL’s typical high-quality and fully-featured Bluetooth 5 implementation supporting AptX HD, LDAC, and UAT codecs. There may be minor differences from the Bluetooth input with very critical listening, but using any of the better codecs dramatically reduces the drawbacks compared to a wired connection.


Ok. So, the DA-9 is small. And it’s got great specs and features. It seems to promise more than it could possibly deliver. Does it actually sound good? Like an actual full-sized stereo amplifier? Would I consider using it in a traditional stereo setup?

Yes. Yes. And, amazingly, yes.

Don’t let the diminutive size and lack of generated heat mislead you. The DA-9 is powerful! I tried it with various stereo speakers, including brutally inefficient, waterproof deck speakers, vintage JBL L-96 (optimistically referred to as bookshelf speakers), large Klipsch KG-4.2 floor-standers, and more reasonably sized Paradigm Monitor 3 SE bookshelf speakers. The SU-9 powered them all, and very well, without breaking a sweat.

The volume control goes from 0-70, and anything above 30 is LOUD with reasonably efficient speakers in average-sized listening spaces. The fact that the DA-9 is rated at 150W @2Ohm load is outstanding, and it should be able to drive almost any speaker you have, with plenty of reserve power on hand.

The noise floor is remarkably low, and even when paired with efficient and sensitive speakers, there is little to no noise without music playing, and the amplifier is set to about mid-range volume (35). This is excellent news for nearfield listening setups with virtually any speaker.

I connected the DA-9 via balanced cables to the SU-9 and listened mainly using the Direct EQ setting (disabling onboard sound-shaping). I found the DA-9 to be natural and very clean sounding. The midrange is neutral and detailed, and the overall impression is uncolored and fresh.

I paired the DA-9 with various DACs I have on hand and obtained satisfactory performance even from the modest Topping D10s DAC connected via the RCA inputs. Output volume does not seem to be dramatically different between using the balanced or single-ended inputs.

Let’s be honest, my tastes weigh more towards the warmth of tubes, so the detailed sound of the DA-9 verges a bit further towards a more sterile, dry, and thin music reproduction than I generally prefer, but the final sound is far more dependent on speaker selection.

I greatly enjoyed the combination of the DA-9 with my pair of restored, vintage JBL L96 monitors (a favorite of mine). The weighty low-end of the classic JBL house sound responded very well to the DA-9’s amplification.

A warmer sounding DAC pairing would also benefit the overall sound signature of the DA-9. At least to my ears.

For low volume and non-critical listening, the SBD EQ setting does well to fill in the sound, but it can become bloated at higher volumes or with bass-heavy tracks. The addition of a small subwoofer, such as the Paradigm Cinema CT, further added to the audio fun and can be dialed in (using the subwoofer’s controls) to flesh out the low-end response of smaller driver speakers.

Where to Buy


Digital amps, eh? I feel like I’ve been exposed to the future of stereo amplification. SMSL is quickly making a name for itself by producing impressively fully-featured and innovative products at affordable price points, and the DA-9 more than lives up to this reputation.

It turns out that powerful home stereo amplification doesn’t have to be large. Nor hot. Nor expensive. The SMSL DA-9 exposes the fallacies in that line of thought.

Instead, a discrete little box can deliver all the audio goods to whatever speakers you hook up to it. Pairing it with the matching SU-9 DAC and SH-9 headphone amplifier, it’s poised to complete a near-perfect trifecta of affordable desktop audio. Even if you want to fill a large room with high-quality audio, the DA-9 has surprisingly potent power hidden in a nondescript but classy-looking container.

Lacking only a large variety of inputs, the DA-9 could easily take over most living room stereo duties. Want a simple Bluetooth-ready kitchen or bedroom stereo able to be hidden away? I can think of few better options.

The DA-9 is a bang-for-the-buck champ and tons of musical fun to be had for a surprisingly reasonable cost.

Author Trav Wilson:  Audiophile or Audio-Phool? I don’t claim to have golden ears with magical properties, nor any ability to create music. But I do have a deep appreciation for music, founded at a young age, and curated over the years. I’m also unapologetically a gear-head and love lights, buttons, meters, switches, and especially things made from traditional wood, leather, metal, and glass materials. As with everything, take it for what it is: this is just one person’s opinion. Runs noteworthy.audio. 

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