Emotiva BasX A2+ Stereo Power Amplifier

The Emotiva BasX A2+ sits within Emotiva's entry-level BasX series, which is designed to bring audiophile-grade performance to budget-conscious systems without compromising on engineering fundamentals. As the two-channel stereo model in the BasX amplifier lineup, the A2+ positions itself above basic receiver-based amplification, offering a dedicated power stage with the headroom and current delivery that separate amplifiers are built to provide.

Circuit Topology and Design Philosophy

The A2+ employs a Class A/B output stage built around a high-current, short signal path topology. Class A/B operation is chosen here for the same reason it is favoured across professional and audiophile designs: it combines the low-distortion characteristics of Class A at low power levels with the thermal and efficiency benefits of Class B at higher output levels. The result is an amplifier that remains composed at moderate listening levels whilst retaining the ability to deliver clean dynamic peaks when the music demands it.

Microprocessor-controlled protection circuitry monitors the amplifier during operation and intervenes only when genuine fault conditions arise, leaving the signal path undisturbed during normal use. This approach avoids the sonic penalty sometimes associated with always-active protection topologies.

Power Supply

The A2+ uses a heavy-duty linear power supply centred on an oversized toroidal transformer. Toroidal transformers are preferred in audio applications over conventional E-I laminated types because their geometry reduces stray magnetic field radiation — which can otherwise induce hum into sensitive amplifier circuitry — and their lower mechanical resonance contributes to a quieter operating environment. The supply is augmented by a bank of ultra-low ESR filter capacitors, which maintain stable voltage under dynamic load conditions and support the amplifier’s ability to drive 4-ohm loudspeakers without significant output sag.

Inputs and System Integration

Each channel is equipped with both a balanced XLR input and an unbalanced RCA input, with one of each provided per channel. Balanced XLR connectivity is relatively uncommon at this price point and is valuable when connecting to processors or preamplifiers with balanced outputs, as the differential signalling architecture rejects common-mode noise picked up along the interconnect run. Input impedance is 27 kΩ, compatible with a wide range of preamplifier output stages.

System integration is further supported by a 12 V trigger input (accepting 5–12 V AC or DC) and a corresponding trigger output rated at 12 VDC capable of driving loads up to 120 mA — allowing the A2+ to switch on and off in concert with a processor or preamplifier. Alternatively, the amplifier can be configured to power up automatically on detection of an audio signal. The unit accepts both 115 V and 230 V mains supplies, making it suitable for worldwide deployment.

Construction

The chassis is constructed from heavy-gauge steel with a milled aluminium faceplate. The internal layout is designed for a short signal path, which minimises the opportunity for parasitic capacitance and inductance to degrade high-frequency performance. Speaker connections are made via audiophile-grade five-way binding posts, accepting banana plugs, spade lugs, or bare wire.

Specifications