- Thread Author
- #1
Hello Everyone,
I wanted to share my review,of the BT20A MAX from Fosi Audio—a compact Class-D amplifier designed for desktop and nearfield setups.
At its core, the BT20A MAX is built around the Texas Instruments TPA3255 chipset, enhanced with Post-Filter Feedback (PFFB) technology. This combination is engineered to deliver low distortion, excellent clarity.
Despite its small footprint, it offers impressive power output—up to 300W per channel peak and around 180W RMS into 4Ω—giving it the ability to comfortably drive a wide range of speakers.
Feature-wise, it includes Bluetooth 6.0 for modern wireless connectivity, along with a subwoofer output supported by an 80Hz high-pass filter, making it well-suited for 2.1 setups.
Another standout aspect is its dual independent power supply design, which separates the analogue and digital stages. This helps minimise interference from switching noise, resulting in a cleaner and more stable audio signal.
Overall, the BT20A MAX aims to strike a balance between size, power, and sound quality.
Packaging
Straight from the box, the BT20A MAX from Fosi Audio makes a strong impression with its sturdy, well-organised packaging that shows clear attention to detail.
Once opened, the amplifier is neatly secured in custom-cut foam, giving it a clean, protected, and orderly presentation from the moment you lift the lid.
Build Quality, Look & Feel
The unit has a solid, well-built feel with an attractive blend of colour tones that gives it a clean, premium appearance. Its weight adds stability, ensuring it stays firmly in place even when connected to cables.
The remote control is lightweight and plastic in construction, but it performs reliably and responds without issue.
The motorised volume control operates smoothly and reacts promptly to remote adjustments, offering a seamless user experience. Bass and treble knobs turn with a nice, even resistance and include a clear centre detent, likely indicating a neutral setting.
An intuitive input selector and mode button make source switching straightforward. The speaker terminals are well spaced, comfortably accommodating thicker speaker cables and interconnects without crowding.
Key Specifications
Amplifier & Architecture
Power Output
Performance Metrics
In the box
Design and Build Quality:
Front Panel
Connectivity and Setup
Back Panel
Remote Control
The Fosi Audio BT20A Max remote is a compact infrared (IR) controller included with the amplifier, giving you full control without needing to use the front panel.
It operates via IR rather than Bluetooth, so it requires direct line-of-sight and must be aimed at the unit, you can reset Bluetooth, switch between inputs, and control playback. It also has the added convenience of being able to control compatible Fosi components such as the P4, ZD3, and ZP3, making it useful in a broader setup."
Remote Functions:
Bluetooth 6.0
The unit comes equipped with Bluetooth 6.0, powered by the Qualcomm QCC3095 chipset, supporting a wide range of high-resolution audio codecs including aptX, aptX HD, aptX Adaptive, aptX Lossless, and LDAC for enhanced wireless sound quality.
Pairing was straightforward, and the connection proved consistently stable throughout use. When tested with an iPhone 13, setup was quick and hassle-free. Once initially paired, the device reliably reconnected automatically whenever the Bluetooth input was selected again, offering a smooth and convenient user experience.
Power Supply / Output
Setup / Test Conditions
Music Playlist
Sound Performance
The BT20A Max delivers a clean, controlled, and neutral-leaning sound signature that works well across a wide range of genres. Its presentation is composed and articulate rather than overly coloured, allowing the character of the source and speakers to come through naturally.
At low to moderate listening levels—where this amplifier is most at home—it performs particularly well, maintaining clarity, balance, and composure without any sense of strain. Even as volume increases, it holds control confidently, with no obvious distortion or harshness creeping in.
My Sound Impressions
1) Bluesound Node 2i (Digital Streaming via Internal DAC)
Using the Bluesound Node 2i for streaming, I listened to a mix of remastered jazz and older recordings. The sound was clean and well balanced from the start. The amplifier gave my speakers the support they needed to deliver good separation, allowing instruments to come through cleanly while still picking up the finer details without sounding overdone.
Bass was tight and controlled, while the treble stayed smooth and easy to listen. What stood out most was the consistency—both modern and older tracks sounded equally good. Overall, a very enjoyable and easy listen, especially for jazz.
2) CD Player (Classical Music)
With classical recordings, the BT20A Max handled dynamic shifts better than expected for a compact Class-D amplifier. It maintained composure during more complex passages, preserving clarity without congestion.
There was a good sense of space between instruments, and quieter sections transitioned smoothly into louder crescendos without losing control. Strings in particular came through with a natural tone, contributing to a relaxed and immersive listening experience.
3) Turntable (Vinyl – Black Sands)
Vinyl playback felt natural and engaging, with a smooth tonal balance that suited extended listening. The amplifier didn’t add noticeable coloration, allowing the character of the recording to come through while maintaining clarity and control.
4) Bluetooth (iPhone 13 – Spotify Streaming)
Connecting an iPhone 13 via Bluetooth and streaming through Spotify worked smoothly. The connection stayed strong, even from about 10 metres away in another room, with no dropouts. While limited to AAC on the iPhone, sound quality remained clear and balanced—more than adequate for casual listening. It doesn’t quite match wired sources in refinement, but it’s convenient and performs well within expected limits.
Final Verdict
The BT20A Max has excellent build quality with a solid, well-made feel. Its sleek, minimalist design makes it visually appealing and easy to display on a shelf alongside other hi-fi gear. The chassis feels sturdy and premium, with no sense of cheapness, and the controls—especially the volume knob—are firm and well-constructed without any wobble.
While it lacks a digital input for direct TV connection, the core performance is what stands out most. Sonically, it exceeded expectations. Connected to a turntable, CD player, and digital streamer, it drove the speakers effortlessly and delivered a clean, dynamic, and enjoyable sound. It handled vintage speakers particularly well, producing a lively and engaging presentation with more than enough power for a typical listening space.
The unit is also very user-friendly, with straightforward operation and a remote control that makes it ideal for desktop or nearfield listening setups. Overall, it combines strong performance, thoughtful design, and solid construction, making it a highly recommended amplifier for anyone looking to build a compact yet capable audio system.
Demo -
I wanted to share my review,of the BT20A MAX from Fosi Audio—a compact Class-D amplifier designed for desktop and nearfield setups.
At its core, the BT20A MAX is built around the Texas Instruments TPA3255 chipset, enhanced with Post-Filter Feedback (PFFB) technology. This combination is engineered to deliver low distortion, excellent clarity.
Despite its small footprint, it offers impressive power output—up to 300W per channel peak and around 180W RMS into 4Ω—giving it the ability to comfortably drive a wide range of speakers.
Feature-wise, it includes Bluetooth 6.0 for modern wireless connectivity, along with a subwoofer output supported by an 80Hz high-pass filter, making it well-suited for 2.1 setups.
Another standout aspect is its dual independent power supply design, which separates the analogue and digital stages. This helps minimise interference from switching noise, resulting in a cleaner and more stable audio signal.
Overall, the BT20A MAX aims to strike a balance between size, power, and sound quality.
Packaging
Straight from the box, the BT20A MAX from Fosi Audio makes a strong impression with its sturdy, well-organised packaging that shows clear attention to detail.
Once opened, the amplifier is neatly secured in custom-cut foam, giving it a clean, protected, and orderly presentation from the moment you lift the lid.
Build Quality, Look & Feel
The unit has a solid, well-built feel with an attractive blend of colour tones that gives it a clean, premium appearance. Its weight adds stability, ensuring it stays firmly in place even when connected to cables.
The remote control is lightweight and plastic in construction, but it performs reliably and responds without issue.
The motorised volume control operates smoothly and reacts promptly to remote adjustments, offering a seamless user experience. Bass and treble knobs turn with a nice, even resistance and include a clear centre detent, likely indicating a neutral setting.
An intuitive input selector and mode button make source switching straightforward. The speaker terminals are well spaced, comfortably accommodating thicker speaker cables and interconnects without crowding.
Key Specifications
Amplifier & Architecture
- Channel: 2.1
- Architecture: Class-D with PFFB (Post-Filter Feedback)
- Chipset: TI TPA3255, NE5532
Power Output
- RMS Output Power: 180W × 2 @ 4Ω
- Max Output Power: 300W × 2 @ 4Ω
- Terminal Impedance: 2–8Ω
- Inputs: RCA 1 / RCA 2 / Bluetooth
- Outputs: Speaker Out / Sub Out
- Bluetooth SoC: Qualcomm QCC3095
- Bluetooth Version: 6.0
- Range: ≤ 15 m (50 ft)
- Audio Codecs: SBC / AAC / aptX / aptX HD / aptX Adaptive / aptX Lossless / LDAC
Performance Metrics
- Signal-to-Noise Ratio (SNR): ≥ 112 dB
- Total Harmonic Distortion + Noise (THD+N): ≤ 0.003%
- Voltage Range: DC 32 V–48 V
- Cooling: Active internal cooling fan
- Dual independent power supply
- Switchable 80Hz High-Pass Filter (HPF)
In the box
- Contents: BT20A MAX
- 48v 5a Gan power supply
- Remote control
- Bluetooth antenna
- User manual.
Design and Build Quality:
Front Panel
- Motorized analogue potentiometer
- Bass, Treble controls knobs
- Multifunction Button: Power ON/Off & input selector - BT , RCA 1 , RCA 2 Input
- 3 input channels. with a series of LEDs lights that indicate the current selected input.
Connectivity and Setup
Back Panel
- Two RCA inputs.
- Bypass button to turn the equalizer on and off.
- Sub output
- Speaker banana sockets outputs. - holds the plugs well
- HPF Toggle: 80 Hz fixed High Pass filter, with two Settings: 80Hz or OFF
- 12v Trigger Input
- BT Antenna input
- Power Input plug
Remote Control
The Fosi Audio BT20A Max remote is a compact infrared (IR) controller included with the amplifier, giving you full control without needing to use the front panel.
It operates via IR rather than Bluetooth, so it requires direct line-of-sight and must be aimed at the unit, you can reset Bluetooth, switch between inputs, and control playback. It also has the added convenience of being able to control compatible Fosi components such as the P4, ZD3, and ZP3, making it useful in a broader setup."
Remote Functions:
- Power On/Off:
- Input Switching: Allows you to switch between Bluetooth and RCA inputs.
- Volume Control: Increases or decreases the volume by controlling the motorized knob.
Bluetooth 6.0
The unit comes equipped with Bluetooth 6.0, powered by the Qualcomm QCC3095 chipset, supporting a wide range of high-resolution audio codecs including aptX, aptX HD, aptX Adaptive, aptX Lossless, and LDAC for enhanced wireless sound quality.
Pairing was straightforward, and the connection proved consistently stable throughout use. When tested with an iPhone 13, setup was quick and hassle-free. Once initially paired, the device reliably reconnected automatically whenever the Bluetooth input was selected again, offering a smooth and convenient user experience.
Power Supply / Output
- Peak output power: 300 W × 2 @ 4 ohms
- RMS power: 180 W × 2 @ 4 ohms
- Power supply: DC 32–48 V
Setup / Test Conditions
- Sources: Turntable, CD Player, Streamer
- Use case: medium room 2m x 4m and listening 2 m from speakers
- Speaker placement 180cm part
- Revox AX 5-4 (3-way Speaker Impedance: 4 Ohm)
Music Playlist
- Jazz - Take Five" by The Dave Brubeck Quartet – Streaming via Bluesound Node 2i
- Classical - Tchaikovsky: Symphony No. 6 - CD
- Electronica - Bonobo, Black Sands - Vinyl LP Record
Sound Performance
The BT20A Max delivers a clean, controlled, and neutral-leaning sound signature that works well across a wide range of genres. Its presentation is composed and articulate rather than overly coloured, allowing the character of the source and speakers to come through naturally.
At low to moderate listening levels—where this amplifier is most at home—it performs particularly well, maintaining clarity, balance, and composure without any sense of strain. Even as volume increases, it holds control confidently, with no obvious distortion or harshness creeping in.
My Sound Impressions
1) Bluesound Node 2i (Digital Streaming via Internal DAC)
Using the Bluesound Node 2i for streaming, I listened to a mix of remastered jazz and older recordings. The sound was clean and well balanced from the start. The amplifier gave my speakers the support they needed to deliver good separation, allowing instruments to come through cleanly while still picking up the finer details without sounding overdone.
Bass was tight and controlled, while the treble stayed smooth and easy to listen. What stood out most was the consistency—both modern and older tracks sounded equally good. Overall, a very enjoyable and easy listen, especially for jazz.
2) CD Player (Classical Music)
With classical recordings, the BT20A Max handled dynamic shifts better than expected for a compact Class-D amplifier. It maintained composure during more complex passages, preserving clarity without congestion.
There was a good sense of space between instruments, and quieter sections transitioned smoothly into louder crescendos without losing control. Strings in particular came through with a natural tone, contributing to a relaxed and immersive listening experience.
3) Turntable (Vinyl – Black Sands)
Vinyl playback felt natural and engaging, with a smooth tonal balance that suited extended listening. The amplifier didn’t add noticeable coloration, allowing the character of the recording to come through while maintaining clarity and control.
4) Bluetooth (iPhone 13 – Spotify Streaming)
Connecting an iPhone 13 via Bluetooth and streaming through Spotify worked smoothly. The connection stayed strong, even from about 10 metres away in another room, with no dropouts. While limited to AAC on the iPhone, sound quality remained clear and balanced—more than adequate for casual listening. It doesn’t quite match wired sources in refinement, but it’s convenient and performs well within expected limits.
Final Verdict
The BT20A Max has excellent build quality with a solid, well-made feel. Its sleek, minimalist design makes it visually appealing and easy to display on a shelf alongside other hi-fi gear. The chassis feels sturdy and premium, with no sense of cheapness, and the controls—especially the volume knob—are firm and well-constructed without any wobble.
While it lacks a digital input for direct TV connection, the core performance is what stands out most. Sonically, it exceeded expectations. Connected to a turntable, CD player, and digital streamer, it drove the speakers effortlessly and delivered a clean, dynamic, and enjoyable sound. It handled vintage speakers particularly well, producing a lively and engaging presentation with more than enough power for a typical listening space.
The unit is also very user-friendly, with straightforward operation and a remote control that makes it ideal for desktop or nearfield listening setups. Overall, it combines strong performance, thoughtful design, and solid construction, making it a highly recommended amplifier for anyone looking to build a compact yet capable audio system.
Demo -
