Fosi Audio BT20A Pro Review

Fosi Audio BT20A Pro review featured

This is a review of the Fosi Audio BT20A Pro 2-Channel Bluetooth Power Amplifier. This is an updated version of the original BT20A. It’s priced at $99.

There is a 20% off promo code: 20APROMKT20 that will work on both provided purchase links. This code will start valid on 10th April, and expire on 30th April.

Disclaimer: This sample was provided by Fosi Audio for an honest review. All observations and opinions here are based on my experience with the product.

Fosi Audio BT20A Pro Review
The Fosi Audio BT20A Pro Bluetooth power amplifier delivers audio quality well above its price point.
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Bass and treble tone controls
Powerful, clean sound
Small footprint
Bluetooth input
Upgradeable op-amps
No aptX or LDAC
No remote
Our Score

Fosi Audio BT20A Pro

What's in the box
What’s in the Box

BT20A Pro Power Amplifier x1
Bluetooth Antenna x1
Spare Volume Knob x1
32V 5A Power Adapter x1
AC Cord x1
User Manual x1

BT20A Pro design


As well as the internals, the new Fosi Audio BT20A Pro has had an external facelift. Gone is the plain black box aesthetic of the original model with its chintzy dials. This updated version has a sleek space blue finish that I think both looks and feels better than the old chassis.

The front panel has the same familiar layout with a power switch on the left, followed by bass and treble tone controls and a volume knob. But, as I’m sure you’ve noticed already, the volume knob is now a striking copper colour. And I think it looks fabulous. Moreover, the tone control knobs now click firmly into place when they’re in the centre (defeated) position.

On the back, we find the obligatory RCA inputs and speaker binding posts, along with the Bluetooth antenna mount and the DC power jack. But there’s something else new here too: the BT20A Pro comes with a 3.5mm Pre-out. This is brilliant because it means I can now easily add my subwoofer to the setup.

In regards to the updated internals, the BT20A Pro is equipped with the TPA3255 amp chip (the same one found in the TB10D). In addition, the op-amps can be replaced by LME49720HA/MUSES02/OPA26041P/OPA2134PA/LM4562/NJM4556AD adding a lot of customization options.

Connectivity & Setup

The BT20A can receive audio via either its RCA input or Bluetooth. The Bluetooth receiver is limited to SBC and AAC codecs but testing with my iPhone the audio quality was more than acceptable in the context of the price. The amp automatically connects to my phone each time it’s turned on. You can unpair the device by pressing on the volume knob for a few seconds.

First, I paired the BT20A Pro with my SMSL 200 DAC. I then hooked up my trusty NHT C3 speakers and Polk HTS 12 subwoofer. Later, I did some extra testing with my Elac Debut B6 speakers as well.

Fosi Audio BT20A Pro top view


So how does the Fosi Audio BT20A Pro perform? Well, after having experience with some of the brand’s other models (most notably the BT20A), I had high expectations going in. It’s important to remember here that we’re talking about a sub $100 amplifier and that will weigh in, to some extent, on my subjective opinion.

the BT20A Pro packs a lot of power for my bookshelf speakers, more than I’ll ever need, to be honest. It can push them to ear-popping levels that would probably make my neighbours complain (remember to listen at responsible volumes).

The bass and treble tone controls are effective, and the neutral notch in the middle allows for easy resetting. I prefer to keep the tone controls at the neutral position with my NHT C3s.

When I played Daft Punk’s “Lose Yourself to Dance” and cranked up the volume, the BT20A Pro filled the room with clear and powerful sound without any distortion or other issues. It performed brilliantly, and the Fosi amp didn’t even break a sweat.

Whether you’re listening to music, watching a movie, or playing a game, you can be sure that the BT20A Pro will deliver a transparent and detailed sound that faithfully reproduces the original source material. There’s no hiss, hum, or any other kind of noise that can detract from the experience.

Fosi Audio BT20A Pro power switch and tone controls


With its new aesthetic, upgraded internals and 3.5mm pre-out, the Fosi Audio BT20A Pro is a clear upgrade over the original model. Make no mistake about it, this pint-sized amplifier performs at a high level. If you’re looking for an amp for your modest or secondary system, this one is hard to beat.

There is a 20% off promo code: 20APROMKT20 that will work on both provided purchase links. This code will start valid on 10th April, and expire on 30th April.
Fosi Audio

Recommended award

Max Power Output: 300Wx2 @4Ω

SNR: ≥108dB

Terminating Impedance: 2-8Ω

THD: 0.005%

Power Amplifier Chip: TPA3255

Power Supply: 32V 5ADC

Input Range: 24V-48V

Frequency Response Range: 20Hz-20kHz(±1.2dB)

Bluetooth Transmission Range: Up to 50Ft

Bluetooth Codec: AAC/SBC

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