Fosi Audio BT20A Pro Review 4 Ohm TPA3255 BT Amplifier

Monday, April 10, 2023

The newest super compact bluetooth amplifier on the market is a 300 watt beast! It is the BT20A Pro by Fosi Audio - a TPA3255 amplifier with bluetooth functionality. 

The BT20A Pro supports wired input source and bluetooth input source, which means you can stream audio via a smartphone. The Fosi Audio BT20A Pro enclosure is made of anodized aluminium, including the front and rear faceplates, which are removable. 

On the rear, you find two sets of line out banana sockets to connect the BT20A Pro to stereo speakers, as well as stereo RCA line in ports and a "pre-out", which is a preamplification output for a subwoofer. On the back faceplate, there is also a removable bluetooth antenna and a DC input port, which can handle up to 48V according to the specs.

On the front faceplate, the Fosi Audio BT20A Pro is equipped with a flick power switch and three aluminium knobs (1.5cm deep) for controlling volume, treble and bass. The knobs sit on top of standard potentiometers with stops. The volume knob is also clickable - designed for toggling between wired and bluetooth connection. The bass and treble knobs have a smooth and tight tactile resistance for gradual adjustment and integrate a half-way notch to indicate 50% setting. The volume knob has a nice tight resistance too but no notch. 

On the bottom, there are four thick rubber (5mm) isolation pads. The BT20A Pro weighs 553 grams and measures 17cm x 10cm wide x 4cm high. The included laptop-style power supply is a Fosi Audio branded 160W AC adapter (32V/5A). It weighs 462 grams and measures 14cm long x 6cm wide x 3cm thick. It comes with a detachable figure8 250V/3A power cord (1.2 meters) and a power brick attached to a DC barrel connector. 

Performance-wise, the BT20A Pro is a powerful amp for sure. It can pump around 250+ watts per channel out of the box with little distortion. Compared to the original BT20A, it is also a 2-channel bluetooth amplifier but the BT20A Pro is three times more powerful than the standard BT20A.The extra performance boost is achieved, thanks to the Texas Instruments 3255 amp chip, which can bring up power to 300W potentially. That said, you will need a 48V/350W power supply which is not included. The TPA3255 amp chip inside the BT20A Pro doesn't use a LM2575T-12 voltage regulator (like many on the market), instead it uses an XL7015 voltage regulator, which cna handle 48V working voltage.

Potential deal breakers
  • No AAC codec support
  • No USB power connectivity
  • No headphone jack (the K5 Pro Mini has one)
  • No midrange tone control
  • 48V power supply not included
  • Not suitable for 8 ohm speakers

Selling points 
  • Wired input line in
  • 250W+ per channel 
  • Low distortion
  • Class D amplifier
  • Bluetooth 5.0 connectivity 
  • 18 months warranty
  • Replaceable bluetooth antenna (4.5cm long)
  • Power adapter included
  • High signal to noise ratio (SNR) 108dB
  • Subwoofer output
  • Thick rubber isolation pads 
  • Replaceable NE5532 Op-Amp Chip
  • Tight tactile knobs
  • Texas Instruments 3255 amp chip
  • Solid build quality - no rattling noise
  • Metal knobs & metal enclosure
  • On-board controls for volume, treble & bass
You can buy the BT20A Pro from amazon and Fosi Audio and get 20% off using promo 20APROMKT20

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