The ZA3's primary function is to amplify a line-level analogue signal and drive passive speakers. Its Class D architecture combines high efficiency with a compact enclosure, allowing the ZA3 to take up minimal space in both desktop systems and conventional HiFi setups.

Amplification is based on the Texas Instruments TPA3255 chip. The available output power depends on the impedance of the connected speakers, whether the amplifier is operating in stereo or mono mode, and the power supply being used.

A single ZA3 can drive the left and right speakers as a conventional two-channel integrated amplifier. If the system requires a separate amplifier for each channel, mono operation can be selected using the front-panel switch, allowing two ZA3 units to serve as separate left and right monoblocks.

Mono mode is not simply an alternative connection option, but a different configuration of the power amplifier stage. Using two separate amplifiers gives each channel its own unit, enabling a modular system architecture while using identical ZA3 amplifiers for both channels.

The ZA3 can be integrated with conventional RCA sources as well as balanced analogue equipment. This allows it to work with a variety of line-level sources, ranging from a simple DAC to a streamer.

The rear panel features a stereo RCA input along with balanced input connectors supporting XLR and 6.35 mm TRS connections. With a suitable source and cabling, balanced signal transmission can reduce the effects of external electrical interference, which can be particularly important with longer analogue cable runs.

The ZA3 directly drives passive speakers in a two-channel system, while the setup can also be expanded with a separate active subwoofer. This allows the low-frequency range to be supplemented by a dedicated speaker without requiring another multi-channel amplifier.

The rear screw-type speaker terminals are used to connect the left and right passive speakers, while the RCA Sub Out provides a line-level signal for an active subwoofer with its own built-in amplifier.

One of the distinctive features of the ZA3's analogue signal path is the use of replaceable operational amplifiers. Its design allows compatible op-amps to be installed without soldering, enabling certain parts of the analogue stage to be modified.

Replacing the op-amps requires appropriate electronics knowledge, as pin configuration, supply-voltage compatibility, circuit stability and correct installation orientation must all be taken into account. The TPA3255 stage remains responsible for power amplification, while the op-amps operate in specific parts of the analogue signal path.

Effective heat dissipation is important for an amplifier operating inside a compact enclosure. The ZA3 chassis features side ventilation openings and an internal layout that helps promote airflow around the electronics.

The TPA3255's Class D operation provides high efficiency, allowing a greater proportion of the supplied energy to be converted into useful output power than with a conventional linear amplifier topology. The perforations in the enclosure and the lower heat-dissipation surface work together to help manage the thermal load on the internal components.

The ZA3 operates from an external DC power supply, whose output depends on the selected package, meaning the same amplifier can provide different levels of power reserve depending on the supplied or separately used power supply.

The amplifier accepts a DC input voltage range of 24-48 V. A higher-voltage power supply with sufficient current capability can enable higher output power, although the actual value also depends on speaker impedance and the selected operating mode.

In systems built around a DAC, streamer and amplifier, switching each component on and off individually can be inconvenient. The ZA3's 12 V trigger input allows this process to be automated with a suitable control device.

When used with a source equipped with a compatible trigger output, the ZA3's power state can be synchronised with the other components in the system. This can simplify everyday operation, particularly when using two ZA3 amplifiers in a mono configuration or in a system containing several separate electronic components.