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SMSL A300 Stereo Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 41 14.8%
  • 2. Not terrible (postman panther)

    Votes: 152 54.9%
  • 3. Fine (happy panther)

    Votes: 70 25.3%
  • 4. Great (golfing panther)

    Votes: 14 5.1%

  • Total voters
    277

amirm

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This is a review and detailed measurements of the SMSL A300 stereo class D amplifier. It is on kind loan from a member and costs US $196.


SMSL A300 Stereo Amplifier Class D Review.jpg

The A300 is slick looking with flush volume control and switches. Alas, I am not a fan of the blue LED display from aesthetic point of view. It is nice and large though.

SMSL A300 Stereo Amplifier Class D back panel bluetooth USB Review.jpg


I really like the heavy duty binding posts. And for those of you needing subwoofer support, the filtered sub out and mains. It also includes Bluetooth functionality in addition to reading from a USB stick. With two inputs and a remote control, you are set for the modern audio systems of today.

If you are new to these measurements, please watch my video on understanding amplifier measurements.

SMSL A300 Amplifier Measurements
As usual we start with our dashboard:
SMSL A300 Stereo Amplifier Measurements.png


Sum of noise and distortion as expressed in SINAD lands the A300 in the competent but average category:
best stere amplifier measurements.png


best stere amplifier zoom budget measurements.png


Noise floor could be better:
SMSL A300 Stereo Amplifier SNR Measurements.png


We have our usual load dependency which exists in budget class D amplifier implementations:
SMSL A300 Stereo Amplifier frequency response Measurements.png


So depending on what speaker you throw at it, the treble may be a bit bright or subdued. There are some tone controls you may be able to use to compensate.

Crosstalk was surprisingly poor:
SMSL A300 Stereo Amplifier Crosstalk Measurements.png


I would have liked less high frequency intermodulation distortion:
SMSL A300 Stereo Amplifier Multitone Measurements.png

SMSL A300 Stereo Amplifier 19 20 kHz intermodulation distortion Measurements.png


We have decent amount of power into 4 ohm:
SMSL A300 Stereo Amplifier Power 4 ohm Measurements.png


SMSL A300 Stereo Amplifier Max and Peak Power 4 ohm Measurements.png


And naturally a lot less power at 8 ohm (thankfully most speakers are 4 ohm in bass where power is needed the most):

SMSL A300 Stereo Amplifier Power 8 ohm Measurements.png


Our power sweep against frequency shows the dramatic rise in distortion at higher frequencies:
SMSL A300 Stereo Amplifier Power 4 ohm vs distortion Measurements.png


There is likely some audible pop in both power on and off:
SMSL A300 Stereo Amplifier Power on off click pop Measurements.png


Finally, the amplifier is stable at power on:
SMSL A300 Stereo Amplifier Warm up Measurements.png


SMSL A300 BTL Amplifier Measurements
Edit
, as requested, here are the BTL (bridged) measurements, starting with the dashboard:

SMSL A300 Stereo Amplifier Measurements.png

We take a small hit in both noise and distortion. Let's see how much power we get in exchange:
SMSL A300 Stereo Amplifier BTL Power 4 ohm Measurements.png

The amp never clipped and just shut down so hard to determine max power. So let's measure it at 1%:
SMSL A300 Stereo Amplifier BTL Max and Peak Power 4 ohm Measurements.png


Wow, that is nearly 4X as the theory would predict assuming ample power supply current availability. Even 8 ohm benefits that way:
SMSL A300 Stereo Amplifier BTL Max and Peak Power 8 ohm Measurements.png


There is an important down side: the amplifier output impedance further doubles causing even more response error at 4 ohm:

SMSL A300 Stereo Amplifier BTL Frequency Response Measurements.png


Sub Out/Filtered Mains Output Measurements
Edit 2: here are the measurements of the sub output and mains set to filtered:
SMSL A300 Stereo Amplifier BTL Subwoofer Frequency Response Measurements.png


Conclusions
A year ago the A300 would have gotten a "good" performance mark. But we have seen a lot of high performance amplifiers at even lower prices that the absolute performance of the A300 drops to "not bad." Granted, the A300 has much more functionality with inclusion of remote, bass management, etc. So you get to decide what is important to you. Personally I like to see SMSL do much better on amplification front. It is hard as they don't have access to superb platform like they do with DAC chips.

EDIT: the A300 becomes a powerhouse in BTL mode, producing whopping 404 watts into 4 ohm! Alas, the load dependency increases even more potentially rolling off a lot of the high frequencies. Better use equalization to compensate with room measurement.

I am on the fence as far as recommending the SMSL A300.

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Last edited:
Glad you got around to this one. I was thinking it might do better than this. But it's really just "OK" relative to other offerings in the under $250 category. We're getting spoiled.

I think the BTL monoblock functionality is the key point of difference for this one - I am hoping that Fosi explores the idea of some low-cost monoblocks and a control preamp to compete with Schiit's Saga S...or that SMSL revisits monoblocks and does this one better...
 
Amir, did you measure with the display at lowest setting? I found that it results into more noise if on its brightest setting
 
Thanks Amir, very interesting, would have been nice to see some measurement of bridged performance, which is why many bought it.
personally i have two sabaj a20a 2022, using the same chip, this doesn't bode well for me as far as performance is concerned.
This review also answers a question I've always asked myself: Why smsl or sabaj want to have their dacs reviewed immediately but don't seem so hasty to see their amplifiers tested....?
 
Amir, did you measure with the display at lowest setting? I found that it results into more noise if on its brightest setting
I did test it at the lowest setting. I set it to max for the photo.
 
For the price, it's actually not that bad, especially if you can get one used. Wish SMSL would up their amplifier game though, because they make some great DACs/ Headphone amps
 
Thanks Amir, very interesting, would have been nice to see some measurement of bridged performance, which is why many bought it.
Oh. I was just going to pack and ship it. But have not heard from the owner so maybe I keep it and run that test later today.
 
This is another one where on absolute terms, I'd vote "not terrible", but taking price into consideration, I'd vote "fine".

The fact that it can't hit its advertised power output and the weirdly high crosstalk ultimately pushed me to vote "not terrible".
 
To me it looks like a bargain: A 50 wpc amp with 80 db sinad, sub outs for l.t. $250. Combine with any cheap $100 Dac, and get a pair of OG LS 50's which are now selling for $300 pr, add an SV 1000 sub for $500-600, and you have a legitimate, good looking high performance 2 channel system for around $1200-1400.
 
Agreed. The world needs better chip amps for the masses, like what happened with DACs and opamps one can buy cheap and good these days.
 
I bought this one without measurements a while back since it had all the features I needed. I haven't had any usability complaints with it other than the IR receiver window needs to be bigger, I guess.
 
Are the subouts filtered? I see one is labeled Sw, what is the other?
 
Are the subouts filtered? I see one is labeled Sw, what is the other?
I will see if I can measure it but the doc says not only is the sub out filtered, but you can also filter the mains. The other two sets of RCAs are the two stereo inputs.
 
I will see if I can measure it but the doc says not only is the sub out filtered, but you can also filter the mains. The other two sets of RCAs are the two stereo inputs.
Very curious about the filtering. I assume it isn't adjustable.
 
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Are the subouts filtered? I see one is labeled Sw, what is the other?
The other output is used to output the right channel signal when using the amp in bridged mode.
(I'm assuming you meant the output directly above the SW out)
 
Poor for load dependency. Wonder if we'll see some cheap class d that doesn't have it.

Amir you're in a really spot to test the extent of load dependency on actual speakers. I don't believe anyone has done any in depth testing on it. IME it can be a major problem.
 
Amir you're in a really spot to test the extent of load dependency on actual speakers. I don't believe anyone has done any in depth testing on it. IME it can be a major problem.
Every speaker is different. As a result testing with any real speaker won't tell you much unless you buy that exact speaker.
 
I woke up today feeling off, kept making mistakes. Sure enough, I made an impulse purchase of this amp (instead of the Fosi v3/ 48volt for my pair of Elac db62s ) just an hour before this review was posted. I prioritized the remote and extra rca for my turntable, thinking it couldn’t be worse than the v3. Amazon has already shipped it, and it’ll be here tomorrow morning - so my question is should I just return it for the Fosi?
 
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