SMSL AO300 PRO Review

Petros LaskisUpdated October 7, 20266 Mins read10

Today’s review is about the SMSL AO300 PRO, a compact and affordable 2-channel speaker amplifier capable of delivering 85W×2/8Ω, doubling to 165W×2/4Ω. This is essentially an integrated amplifier that also includes a DAC, a headphone amplifier and Bluetooth wireless connectivity.

The review sample was kindly provided free of charge in exchange for an honest review. I didn’t receive monetary or any other kind of compensation and I don’t use affiliate links.

The price of the SMSL AO300 PRO is $279 and is available exclusively from Aoshida Audio.

You can use the ichosreview-AO300Pro code to get a 5% discount.

SMSL AO300 PRO

SMSL has extensive experience in making compact yet powerful, power efficient and affordable 2-channel speaker amplifiers based on Class D topology.

Their latest model is the AO300 PRO, an upgraded version of the original AO300 that now supports the HDMI eARC protocol, volume adjustment in eARC mode, and TVs with CEC for linked power on/off functionality in eARC mode.

If you are not familiar with SMSL audio, please click here to read our past reviews and get acquainted with the brand.

Technical Overview

At the very heart of the SMSL AO300 PRO beats the Infineon MA5332MS, an integrated 2-channel Class D analog amplifier chip that produces 85W×2/8Ω or 165W×2/4Ω with a THD+N as low as 0.003%.

This chip is very efficient, with minimal power consumption and very low heat generation. The device has a built-in switching power supply, so you get the full output power without the need to upgrade the external power adapter, as it usually happens with similar Class D amplifiers.

Volume control is assigned to the NJW1194 chip by the Japanese brand JRC, while there is an integrated CS43131 DAC chip that also handles headphone amplification. SMSL made sure to equip the AO300 PRO with a dedicated XMOS XU316 USB receiver that can handle 32-bit/768kHz PCM, DSD256 and MQA decoding.

Design and Build Quality

The SMSL AO300 PRO is a compact-sized device that measures 219×42×185mm and weighs 1.499kg, which is enough to keep it stable when using heavy and bulky cables.

The entire chassis is made from CNC-machined aluminum alloy with a smooth black anodized finish. The front panel is also available in a silver finish. On the left side of the front, there is a small LCD screen covered by a high-quality glass panel. The multifunction knob is made from aluminum alloy.

As is usually the case with SMSL, the AO300 PRO is a very well-made piece of equipment that looks and feels more premium than its price would suggest.

Connectivity

As a pure analog amplifier, the AO300 PRO accepts line-level signals through a single stereo RCA line input and has a pair of stereo speaker outputs. The binding posts are compatible with banana and spade connectors, as well as bare wire, but they are small in size and the available space is a little cramped.

There is also a subwoofer output, although SMSL doesn’t specify its working frequency. On the front panel, there are both 6.35mm and 4.4mm headphone outputs, but the latter is not truly balanced. It is provided for extra convenience, so you don’t have to use an adapter.

The digital section supports USB-C, coaxial, optical and HDMI eARC inputs, while Bluetooth 5.3 multipoint wireless reception is also available through the LDAC, aptX HD, aptX, AAC and SBC codecs. The Bluetooth connection is stable and works fine within the same room that I have tested its performance. As it usually happens, audio quality is good but not up to the wired standards.

User Interface and Features

You can control the device either with the multifunction knob or, even better, with the included remote control.

The basic functions are selecting the input and output modes. Plugging in headphones will not mute the speakers; you must select the headphone output mode in order to listen through them. Each output mode remembers and saves its own volume setting.

Additionally, you can switch the screen on or off, select one of the eight different interface colors, and enable or disable the CEC function.

There are five digital filters to choose from, including a NOS (non-oversampling) filter, as well as a simple EQ with eight presets: Direct, Tone, SDB, Bass, Super Bass, Rock, Soft and Clear. You can also independently adjust the Treble and Bass within a range of -09dB to +09dB.

Listening Impressions

I have first tested the AO300 PRO as an amplifier connected to an external DAC (the Aune S18 EVO reference DAC) and then with its internal DAC. The device was tested with the Audio Physic Spark speakers that are roughly 20 times more expensive and have a rating of 4Ω/88dB, not a particularly easy load.

As an Analog Amplifier

This is why I was genuinely surprised to find out how skilful and powerful the AO300 PRO was. It might not have the endless power reserves and huge headroom of my Kinki EXM1 integrated amplifier, but it did very well driving the speakers, delivering punchy, controlled and undistorted bass. I wasn’t able to make it clip in the higher frequencies, even when I pushed it to its limits. The amplifier is also dead silent and doesn’t produce any hissing noise, even at the maximum volume setting.

The overall sound signature of the amplifier can be described as dead neutral. The frequency response is absolutely flat, the amp doesn’t add or remove anything from the input source that would alter its tonal character. The AO300 PRO doesn’t emphasize second or third order harmonics, so this is not an amplifier that you can use to shape the timbre. At the same time, it doesn’t sound particularly cold or clinical, nor does it add artificial brightness, as some competitive amplifiers do.

Very accomplished…

The amp is fast and technically accomplished, remaining controlled and composed even with the most demanding material. It is also surprisingly well resolving, although with a tendency to make the presentation a little analytical. It also has a habit of trimming and stripping the sound of some of its weight and body. Compared to the resident amplifier, the sound is rather dry, lean and flat, but not boring.

The stage is open and spacious enough but not particularly grand or holographic. The center image is quite solid, imaging is up to the task, the amp does well into projecting the size of the ensemble, but there are no depth cues and the images are small, failing to establish a believable sense of realism.

All that said, considering the price of the AO300 PRO and that it is not made to drive $6K high-end speakers but considerably more affordable models, I would rate the overall performance as very satisfying, without much to complain.

The DAC and Headphone Amplifier

For users who don’t own an external DAC, the SMSL AO300 PRO has its own one built-in, so they can start listening to their favorite music straight out of the box, or for added convenience when they want to connect a TV through HDMI.

The overall sound signature is similar as when using an external DAC, but the presentation feels a bit flatter, drier and more clinical, with less sonic weight and slightly restrained dynamics.

The inclusion of an internal DAC is the right decision that can help a lot of newbies take their first steps without the need to buy anything else except speakers, however using a higher-quality external DAC is highly recommended to get the most out of this little amp.

The headphone output is also a welcome feature for late-night listening, but don’t expect much, as there is no dedicated amplification circuit. The output is derived directly from the DAC chip, and the performance is similar to that of an entry-level USB DAC dongle. Output power is also limited, and the headphone jack is better used with earphones or very sensitive headphones.

In The End

Many readers will argue that an entry-level integrated amplifier from a mainstream brand, like the Yamaha R-S202D ($299), will probably sound more pleasing. However, such amps usually produce higher distortion, are not as effective with 4Ω loads, are much bigger and lack the extra features of the SMSL AO300 PRO.

Instead, the SMSL AO300 PRO produces 85W×2/8Ω or 165W×2/4Ω with a THD+N as low as 0.003%, has a built-in DAC, HDMI eARC support, Bluetooth connectivity, and is also compact enough for desktop use.

Anyone looking for all these features in an affordable package, and also value reference neutrality, should definitely audition the SMSL AO300 PRO.

Test Playlist

Authored by Petros Laskis for Ichos Reviews. All content is original and copyrighted. Republishing full reviews or portions without written permission is prohibited. Excerpts up to 100 words are allowed with a direct link.