Getting a stereo setup which keeps the price down without giving up on quality is now easier than ever, thanks to a multitude of very affordable amplifiers which still offer great sound quality. That is the case with the SMSL PA40, too: this latest child of the collaboration between SMSL and Aoshida Audio is simple in terms of the features it offers, but it doesn’t compromise on quality while still being super affordable.
Disclaimer: Aoshida Audio kindly sent me a free unit to write this review. They sell the PA40 for $139. Additional information is available on SMSL’s website.
TL;DR: recap
| Pros |
Cons |
| + Well-built with captivating design
+ Large power output + Neutral sound signature + Remote |
– Slightly worse specs than direct competitors
– No XLR input |
Rating: 9/10
Packaging & Accessories
The plain cardboard box contains just the amplifier, a kettle lead and a remote.
Design & Build
The SMSL PA40 offers the same “floating display” design as the latest devices in SMSL’s line-up, like the DO100 Pro or the DO400. This means that the front of the device is made of a single metal piece which has a “wave” on the left hand side that makes the screen appear like it’s floating in front of the… well, front. It’s a clean and minimalistic design which goes well with any other devices and in all settings.
The front of the device hosts the screen and a status LED on the left hand side, and a volume wheel on the right hand side; the back is home to stereo RCA inputs, speaker outputs and the power connector and power switch.
The chassis is well-built and it looks and feels robust and sturdy. As it’s entirely made of metal, it also works as a heat sink to help disperse the heat produced by the internal components; however, it never gets more than slightly warm to the touch, even after hours of operation.
The screen is a numerical OLED which only shows you the volume level; contrary to other recent devices by SMSL, there is no LCD here – this is where you can see that the PA40 is a more budget-conscious device. The screen has good enough brightness that you can see it clearly even with the sunlight shining directly on it; you can also reduce the brightness to the point it is barely noticeable in a dark room.
The volume wheel is a stepped actuator that spins infinitely, as volume is controlled digitally; it offers physical and acoustic feedback when you turn it, and you can adjust volume in 1 dB increments.
Features & Specs
The PA40 is a pure amplifier that has no onboard DAC: it only takes input via the two RCA connectors on the back. This means you will have to provide the signal through another device, presumably a DAC or another device with analogue output.
SMSL PA40 |
| Input | RCA |
| Suitable speaker impedance | N/A |
| Maximum output power | 165 W p.c. (declared, @ 4 Ω) 85 W p.c. (declared, @ 8 Ω) |
| Frequency response | N/A |
| THD+N (@1 kHz) | < 0.004% |
| SNR | > 100 dB |
| Crosstalk | 72 dB |
The SMSL PA40 is built around an integrated amplifier chip but, unlike most of the competition, it’s not a Texas Instruments TI3255. In this case we have an Infineon MA5332MS, which is the same chip used on the much more expensive SMSL AO300. This is why the power output is identical between the two (although the rest of the specs aren’t, as they depend on the implementation of everything else).
Purely in terms of specs on paper, the PA40 fares worse than alternatives priced in the same bracket such as the LEAUDIO Cattle Pro. This difference, however, is below the threshold of audibility and therefore it does not have any impact on the perceived sound.
Just like all of recent SMSL’s amplifiers and DACs, the PA40 includes a remote, too. The remote allows you to power the unit on and off, to navigate through the menus with a D-pad, to select the input, to mute the output and to adjust the volume.
Sound
I tested the SMSL PA40 by coupling it with an SMSL DO100 Pro and using it to power a pair of ELAC DBR62 speakers.
When it comes to sound, the SMSL PA40 comes across – entirely unsurprisingly – as perfectly neutral. It is virtually indistinguishable from recent Class D competitors based on similar amplifier chips, as its completely flat frequency response does not have any effect on that of the speakers. It just stays entirely out of the way, which is great as it allows you to focus on the music. There is also no background hiss which helps with quieter music.
The power on tap is enough to drive most speakers without issues; in fact, I have to keep volume very low as the DBR62 otherwise become painfully loud.
Final Thoughts
The SMSL PA40 is a capable amplifier that sits just above the entry level of the market, while still offering great performance and a good variety of features. In terms of sound, the output is very clean with no background hiss; it is also entirely neutral, which means you can pair it with any speakers out there. The fact that it is also quite small makes it easy to fit it in both desktop and living room setups with ease.
Overall, much like most recent SMSL products, it is a thoroughly likeable device which offers quite a good bang for your buck. It works really well and it looks good while at it – what’s not to like? I recommend the PA40 for anyone looking for an affordable amplifier which offers all the basic features you need and keeps the price down. It’s hard to go wrong with it.
