Fosi Audio BT20A Review 2 Channel Integrated Amplifier

Wednesday, August 31, 2022

There's some unbelievable amplifier performance to be had for very little coin these days! Take for instance, the Fosi Audio BT20A - a small 2 channel integrated bluetooth amplifier perfect for reviving an old set of passive speakers (e.g. Yamaha Ns244, Dahlquist DQ-10, Realistic Optimus )!

The Fosi Audio BT20A is versatile and very configurable, allowing you to create your own system combination such as external DAC > external 4-band tone control > headphone amplifier > Fosi Audio BT20A.  You can even add a Raspberry Pi to compatible DAC such as the HiFiBerry DAC2 HD). For a TV setup, simply run the cables from the TV to the Fosi Audio BT20A or via an external DAC (e.g. Schiit Modi)

The Fosi Audio BT20A delivers great stereo imaging and deeply immersive bass when paired to speakers with built in amplification to power the midrange to low end frequencies. This massively improves the performance of lossless high resolution audio streaming and over-the-air television.
Being a chip based amplifier, the Fosi Audio BT20A uses a chip and no traditional linear transistors, making it highly more efficient than an old school amplifier, which is a good selling point specially with current rising energy prices. You can use any power supply (even a laptop charger) as long as it is between 12V and 24V, which is needed in order to properly drive 8 ohm speakers. With a 2 ohm speaker, you can use a 12V power supply. 
On the back of the Fosi Audio BT20A, there is a removable faceplate housing the connectivity ports: red/white RCA line inputs, a removable wireless antenna, a DC power port and banana plugs for connecting two speakers. On the bottom of the Fosi Audio BT20A, there is four thick rubber feet to isolate the amplifier and minimize noise vibrations.
On the front of the Fosi Audio BT20A, there is also a detachable metal faceplate with a metal toggle switch, volume knob and tone controls: bass knob and treble knob. The rear and front faceplate easily detach by undoing the hex screws, giving you access to the amplifier board (should you need to replace it). The knobs have a tactile resistance for gradual adjustment. Dimensions of the Fosi Audio BT20A amp is 13cm deep (including the knobs and antenna), 9cm wide and 4cm high - weighs 328 grams (similar to the Fosi Audio K5 PRO Mini DAC amp). The buttons and rear facing banana plugs stick out 1.5cm outward. 
The Fosi Audio BT20A is a neat little powerhouse at an affordable price, proving that you don't have to spend hundreds or thousands in order to get a good sounding amplifier.

Potential deal breakers
  • Does not integrate a headphone jack for headphone connection, unless you use a bluetooth receiver headphone amplifier
  • Uses a switching power supply, which generates buzzing noise at max volume. You can buy a proper transformer to solve this problem but they can cost  quiet a bit - even more than the Fosi Audio BT20A itself!
  • You can only wire a maximum of 2 speakers
  • Does not support Bluetooth multipoint - can only connect to one bluetooth device at a time
  • Audio quality in bluetooth mode is not as good as AUX mode. You can improve the bluetooth audio though, by using an external LDAC bluetooth receiver, which is probably cheaper than buying a chip based amplfier with LDAC, APTX or AAC support

Selling points for the Fosi Audio BT20A
  • Based on Texas Instruments TPA3116D2 class D amplifier 
  • Supports 100 watts per channel
  • Good sound for the price and size - delivers better sound than a classic big amplifier
  • Strong bluetooth connection when connected to a bluetooth 5.0 source
  • Supports banana plug connection
  • Metal aluminum enclosure and tone control knobs
  • Very affordable
  • Perfect for enhancing music and action movies
  • Switching power supply is not as heavy as a classic transformer
  • Consumes less electricity than a classic Hifi amplifier 
  • Can be connected to an old SACD DVD audio player (e.g. Pioneer Elite)
  • Automatic switching  between wireless and wired mode
  • Useful user guide with diagrams showing you how to setup the Fosi Audio BT20A
  • Supports phone streaming via Bluetooth
  • Includes 108 watt (24V/4.5A) power supply
  • Capable of driving 2 ohms and 8 ohm speakers
  • Very good signal-to-noise ratio (98dB)
  • Can be connected to a bluetooth DAC to improve the audio quality
  • Can be connected to a TV
  • Can be converted into a 2.1 channel by connecting the speaker line levels into a subwoofer and speaker line out from the subwoofer
  • 18 month warranty
Accessories include a removable plastic radio antenna and Fosi Audio branded AC adapter, which comes with two cables: a fixed DC barrel cable (1 meter) and detachable figure8 power cord (1.3 meters). The dimensions of the AC adapter are 14cm long, 6cm wide and 3.5cm thick (and weighs 415 grams). You can buy the Fosi Audio BT20A from amazon. There is also a non-Bluetooth version of this 2 channel amplifier.

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