The Fosi Audio ZA3 Balanced 2.1-Channel Power Amplifier delivers powerful Class-D performance with a Texas Instruments TPA3255 chip, providing 155 watts per channel into 4 ohms in stereo mode or 235 watts in mono mode with the included 48V/5A power supply. Featuring balanced XLR/1/4-inch TRS inputs, RCA connectivity, a powered subwoofer output, and a 12V trigger input, the ZA3 offers versatile integration into stereo and 2.1-channel audio systems. Premium audio components, five replaceable op-amp positions, and advanced heat dissipation make this compact amplifier an excellent choice for audiophiles seeking customizable, high-performance amplification.
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Fosi Audio ZA3 Balanced 2.1-Channel Power Amplifier

Experience powerful, high-fidelity sound with the Fosi Audio ZA3 Balanced 2.1-Channel Power Amplifier, a compact yet versatile Class-D amplifier designed for audiophiles looking to build or upgrade a stereo Hi-Fi system. Powered by the Texas Instruments TPA3255 amplifier chip, the ZA3 delivers 155 watts per channel into 4 ohms in stereo mode or 235 watts into 4 ohms in mono mode when paired with its included 48V/5A power supply. With balanced XLR and 1/4-inch TRS inputs, standard RCA connectivity, and a dedicated powered subwoofer output, the ZA3 combines impressive amplification performance with the flexibility to accommodate a wide range of audio systems.

Designed with versatility in mind, the ZA3 features switchable stereo and mono operating modes, allowing it to power a pair of passive speakers or operate as a dedicated monoblock amplifier. For listeners looking to expand their system, two ZA3 amplifiers can be configured in mono mode to independently power the left and right speakers. The balanced XLR/TRS combo inputs provide improved resistance to electrical interference and unwanted noise, making the ZA3 an excellent companion for compatible DACs, preamplifiers, and other high-quality audio components. A dedicated RCA subwoofer output also makes it easy to add a powered subwoofer for deeper bass and a more immersive 2.1-channel listening experience.

Inside its compact aluminum alloy chassis, the ZA3 incorporates premium components, including Japanese NCC and ELNA capacitors, German WIMA capacitors, and Japanese Sumida inductors. Its carefully optimized circuitry delivers a signal-to-noise ratio of at least 106dB, total harmonic distortion below 0.006%, and a SINAD rating of 89dB for clean, detailed sound reproduction. Advanced heat management uses an enlarged chassis, side-mounted ventilation, and protective dust covers to maintain stable performance during extended listening sessions. Five replaceable DIP8 op-amp sockets also provide the opportunity to customize the amplifier's sound using compatible aftermarket operational amplifiers.

The Fosi Audio ZA3 is equally focused on convenience and everyday usability. A 12V trigger input allows automatic power synchronization with compatible audio components, while a precision taper-A volume potentiometer provides smooth, controlled volume adjustments. Its one-piece aluminum alloy enclosure combines an understated modern appearance with durable construction, making it an excellent fit for desktop audio setups, compact listening rooms, and dedicated stereo systems. Whether you're powering bookshelf speakers, adding a subwoofer, or building a dual-mono Hi-Fi system, the ZA3 delivers flexible, high-performance amplification in a space-saving design.

Specifications

• Brand: Fosi Audio
• Model: ZA3
• Manufacturer Part Number: ZA3-48V5A
• Product Type: Balanced Class-D stereo/mono power amplifier
• Channel Configuration: 2.0-channel amplification with powered subwoofer output for 2.1-channel systems
• Amplifier Class: Class-D
• Amplifier Chip: Texas Instruments TPA3255
• Operating Modes: Stereo and PBTL mono
• Stereo Output Power with 48V/5A Power Supply: 155 watts × 2 into 4 ohms RMS
• Mono Output Power with 48V/5A Power Supply: 235 watts × 1 into 4 ohms RMS
• Stereo Output Power with 32V/5A Power Supply: 95 watts × 2 into 4 ohms
• Mono Output Power with 32V/5A Power Supply: 110 watts × 1 into 4 ohms
• Included Power Supply: 48V/5A DC power adapter
• Supported Input Voltage: DC 24–48V
• Supported Speaker Impedance: 2–8 ohms
• Frequency Response: 20Hz–20kHz (±0.1dB)
• Signal-to-Noise Ratio: At least 106dB
• Dynamic Range: At least 106dB
• Signal-to-Noise and Distortion Ratio (SINAD): 89dB
• Total Harmonic Distortion (THD): Less than 0.006%
• Noise Floor: Approximately 150µV
• Input Sensitivity: 0.775V
• Balanced Audio Inputs: Stereo XLR/1/4-inch TRS combo connections
• Unbalanced Audio Input: Stereo RCA
• Speaker Outputs: Two pairs of binding-post terminals
• Speaker Wire Compatibility: Banana plugs and bare speaker wire
• Subwoofer Output: One RCA line-level output for a powered subwoofer
• 12V Trigger: 3.5mm 12V trigger input for synchronized power operation
• Input Selection: Switchable RCA and balanced inputs
• Volume Control: Taper-A potentiometer
• Volume Memory: Remembers the previous volume setting after powering off
• Replaceable Op-Amps: Five swappable DIP8 dual operational amplifier positions
• Op-Amp Locations: Left channel, right channel, balanced input, and subwoofer signal stages
• Compatible Op-Amp Examples: Sparkos SS3602, MUSES02, OPA2604, OPA2134PA, OP249, AD827, LM4562, and other compatible DIP8 dual op-amps
• Capacitors: Japanese NCC, Japanese ELNA, and German WIMA components
• Inductors: Japanese Sumida components
• Circuit Design: Optimized internal layout to minimize interference between audio circuitry sections
• Cooling System: Side-mounted ventilation with protective dust covers and an enlarged heat-dissipating chassis
• Chassis Material: Aluminum alloy
• Construction: One-piece molded enclosure with sandblasted exterior finish
• Dimensions: Approximately 6.1 × 7.2 × 2 inches (15.5 × 18.4 × 5.1cm)
• Listed Weight: Approximately 3.92 lbs (1.78kg)
• Bluetooth Connectivity: No
• Wi-Fi Connectivity: No
• Built-In DAC: No
• Phono Preamplifier: No
• EAN: 6976136960270
• Manufacturer Warranty: 24-month limited warranty
• Included Accessories: Fosi Audio ZA3 power amplifier, 48V/5A power adapter, power cord, and user manual

What It's Great At

• Powerful Class-D Stereo Amplification: The Texas Instruments TPA3255 amplifier chip delivers 155 watts per channel into 4 ohms with the included 48V/5A power supply, providing substantial power for compatible passive bookshelf and floorstanding speakers.
• Flexible Stereo and Mono Operation: Switch between traditional two-channel stereo amplification and 235-watt mono operation, or pair two ZA3 amplifiers for a dedicated dual-mono Hi-Fi system.
• Balanced High-Fidelity Audio Connectivity: XLR and 1/4-inch TRS combo inputs provide noise-resistant balanced connections for compatible DACs and preamplifiers, while standard RCA inputs offer straightforward integration with traditional audio sources.
• Easy 2.1-Channel System Expansion: A dedicated RCA subwoofer output allows the ZA3 to connect to a powered subwoofer, bringing additional low-frequency impact to music, movies, and everyday listening.
• Customizable Audiophile Performance: Five replaceable DIP8 op-amp positions let enthusiasts experiment with compatible operational amplifiers to tailor the ZA3's sonic characteristics to their preferences.
• Premium Components and Efficient Cooling: High-quality Japanese and German audio components, an optimized circuit layout, and upgraded side ventilation support clean, stable amplification in a compact aluminum chassis.

FAQ Section

Q: How much power does the Fosi Audio ZA3 deliver?
A: With the included 48V/5A power supply, the Fosi Audio ZA3 delivers 155 watts per channel into 4 ohms in stereo mode or 235 watts into 4 ohms in mono mode. Output power varies depending on the connected speaker impedance, power supply, and operating configuration.

Q: Can the Fosi Audio ZA3 operate as a monoblock amplifier?
A: Yes. The ZA3 features a switchable mono mode that allows it to function as a dedicated monoblock power amplifier. Using two ZA3 units in mono mode allows each amplifier to power an individual speaker, creating a dual-mono stereo system with independent amplification for the left and right channels.

Q: Does the Fosi Audio ZA3 support balanced XLR connections?
A: Yes. The ZA3 includes balanced XLR/1/4-inch TRS combo inputs that help reduce unwanted interference and noise when connected to compatible balanced audio equipment. It also features standard RCA inputs for conventional unbalanced audio sources.

Q: Can I connect a subwoofer to the Fosi Audio ZA3?
A: Yes. The ZA3 includes a dedicated RCA subwoofer line output for connecting a powered subwoofer. This allows you to expand a traditional stereo system into a 2.1-channel configuration with additional bass support. The output is designed for powered subwoofers and cannot directly drive a passive subwoofer.

Q: What speakers are compatible with the Fosi Audio ZA3?
A: The ZA3 supports passive speakers with nominal impedances from 2 to 8 ohms. It can be used with many bookshelf and floorstanding speakers, although overall performance depends on speaker sensitivity, impedance, listening volume, and room size. Speaker connections support banana plugs or bare speaker wire.

Q: Can I change the op-amps in the Fosi Audio ZA3?
A: Yes. The ZA3 features five replaceable DIP8 dual op-amp positions, allowing enthusiasts to customize portions of the audio circuitry. Compatible alternatives include models such as the Sparkos SS3602, MUSES02, OPA2134PA, and LM4562. Always verify electrical compatibility, correct orientation, and safe installation procedures before replacing an op-amp.

Q: Does the Fosi Audio ZA3 have Bluetooth or a built-in DAC?
A: No. The ZA3 is a dedicated analog power amplifier and does not include Bluetooth, Wi-Fi, or a built-in digital-to-analog converter. To stream digital music, connect a compatible external DAC, network streamer, or other source component with an appropriate analog output.

Q: Can I connect a turntable to the Fosi Audio ZA3?
A: Yes, but the turntable must have a built-in phono preamplifier or be connected through a separate external phono preamp. The ZA3 does not include a dedicated phono stage, so a turntable's raw phono-level signal must be converted to line level before connecting to the amplifier's RCA inputs.