• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

FOSI BL20A Amplifier Review


New Member
Jan 10, 2023
Product Tested (FOSI provided free of charge):

Fosi BL20A Bluetooth Power Amp
Discover New Standards of Sound in Music and Home Theater
Fosi audio has worked over the years to develop HIFI audio amplifier products that provide an unmatched listening experience. We use top-of-the-line technology and innovative research to bring our customers the best in audio advancements. Fosi Audio brings cinema to your home!

Other products used in test:
Fosi X2 Phono Pre-Amp; Fosi TB10D Amp (Upgraded Version); Mono-Price 9437 Banana Plugs, JBL Control 8 ohm outdoor speakers. Pioneer PL-200 Turntable, Audio Technica LP Gear Cartridge

Initial observations:
Very Small Footprint, speaker binding posts handle 14AWG wire OK, use banana plugs for 12 AWG, need straight plugs for pre-amp out & aux input (I used RCA adapters).
Versatile remote, many features such as select track (USB memory stick), skip to next track, volume etc. Note instead of having a “T” for treble it has “H”; bass is labeled “B”.
Using remote, if you change the tone control settings it will go back to the dial settings if turned off and then back on again.
The Bluetooth worked great with my Samsung phone, tested and worked at 60 feet.

I found that with WAV files there was a slight click out of the speakers when changing tracks with remote, no click when it was a MP3.

Note the tone control dials are not centered, I don't want to try to remove dials and re-center unless FOSI says OK.

You will hear a beep if the volume control is already at max (using remote), observed this when set up as pre-amp.

When I used as a pre-amp in Phono/X-2/BL20A/TB10D series the sound appeared slightly muffled vs not using BL20A in pre-amp mode. Test equipment/meters may be able to verify any deterioration in sound quality.

I found this a great “little” amp with many good features and good sound quality at this price point.

What I didn't like:
Too small a foot print, makes arranging with connecting cable a challenge due to lack of mass/weight.
Tight area for connectors in back
Very small knobs/controls on front.
As you can see, I have three different FOSI products, each are a different dimension (width/depth/height). A uniform footprint (larger) would be better and help with any stacking, arranging.

I plan on using this for a portable sound set-up. When connecting to outdoor speakers the amp can be inside and remote will work through a window.


  • Faceplate.jpg
    183.4 KB · Views: 325
  • Rear.jpg
    175.9 KB · Views: 237
  • Remote.jpg
    119.8 KB · Views: 261
  • Stacked.jpg
    152 KB · Views: 274
Top Bottom