Aiyima A20 Mono Class D Power Amplifier 300W TPA3255 XLR RCA TRS

If you’ve ever thought about building a stereo system with separate mono amplifiers for each speaker, you probably assumed it would cost a small fortune. But what if there was a compact, affordable option that still gives you serious power and pro-grade connectivity? The AIYIMA A20 might be that option.

What the TPA3255 and PFFB Bring to Your Rack

This Class D mono amplifier uses the Texas Instruments TPA3255 chip with PFFB (Post-Filter Feedback). Based on the specs, that means clean power: 300W into 4 ohms, 150W into 8 ohms, SNR ≥100dB, and THD ≤0.01%. Frequency response is 20Hz to 20kHz. And the aluminum chassis measures about 154 x 120 x 50 mm and weighs roughly 1 kg. Here’s the thing — that’s tiny for a mono amp with these ratings.

• Amplifier Chip: Texas Instruments TPA3255
• Feedback Topology: PFFB (Post-Filter Feedback)
• Power Output into 4 Ohm: 300W
• Power Output into 8 Ohm: 150W
• Frequency Response: 20Hz – 20kHz
• Signal-to-Noise Ratio: ≥100dB
• Total Harmonic Distortion: ≤0.01%
• Input Impedance: 10 kOhm
• Inputs: XLR, RCA, TRS
• Outputs: Speaker binding posts, Sub Out
• High-Pass Filter: Yes
• 12V Trigger: Yes
• VU Meter: Yes
• Power Supply Requirement: External DC 24V – 48V
• Recommended Power Supply: 48V 5A or higher
• Chassis Material: Aluminum alloy
• Dimensions: Approx. 154 x 120 x 50 mm
• Weight: Approx. 1.0 kg

A Mono Amp That Plays Well With Other Gear

Connectivity is where the AIYIMA A20 shines. You get balanced XLR, balanced TRS, and unbalanced RCA inputs. That means you can pair it with a preamp, DAC, or receiver without adapters. There’s also a subwoofer output, a high-pass filter, a 12V trigger, and a VU meter. The 12V trigger lets the amp turn on with your system. The HPF sends only higher frequencies to your main speakers while the sub out handles the low end. Honestly, for a mono power amplifier, that’s a lot of integration features. Input impedance is 10 kOhm.

The Power Brick You’ll Need to Bring

Here’s the catch: this amp requires an external DC power supply. The specs say 24V to 48V, with a recommended 48V 5A or higher. That power supply is not mentioned as included, so you’ll likely need to buy one separately. That adds cost and another box behind your rack. Also, remember this is a mono amp. For stereo, you’ll need two. That said, two small mono blocks can still take up less space than one big stereo amp. Fair warning: check whether the seller includes a power supply before you order, because the listing doesn’t spell that out. And if you’re new to mono amps, plan your wiring carefully.

Who Should Consider This TPA3255 Mono Amp

This PFFB TPA3255 power amplifier makes the most sense for someone who wants to experiment with monoblock setups without spending a lot. It’s also a good fit for a desktop system, a small home theater, or a subwoofer amp. If you already own a balanced preamp or a DAC with XLR outputs, you’ll get the most from those inputs. But if you need a simple all-in-one stereo receiver, this isn’t that. It’s a focused, single-channel tool. Judging by the specs, it delivers serious power and clean measurements for its size.

If you’re ready to build a compact, flexible mono amp setup, the AIYIMA A20 is worth a closer look. Just remember to budget for a proper 48V power supply and a second unit for stereo. Check the listing details, and enjoy the clean Class D sound.