• Audiophile quality Class A/B output stage.
• Linear power supply with a hefty toroidal transformer and plenty of filtering.
• Perfect amp to power an impressive small stereo system.
• Great vintage sound for high impedance and difficult-to-drive headphones.
The BasX A2m is a flexible stereo amplifier that combines excellent audio performance with several unique and extremely useful features. The A2m can be used as the foundation of a great small stereo system – with or without a separate preamp. Its small size makes it the ideal solution for situations where space is limited or where multiple two-channel amplifiers will be used to power multiple different zones or sets of surround or height speakers. The A2m also features unique headphone output circuitry which can deliver great sound quality from a wide variety of both normal and difficult-to-drive headphones.
The BasX A2m is a two-channel power amplifier that delivers 50 watts/channel into 8 Ohms, and 90 watts/channel into 4 Ohms, with a rated THD+N of <0.1%, and an A-weighted S/N ratio of 112 db. The BasX A2m features the same high-quality Class A/B amplification and full-sized five-way speaker binding posts as other BasX power amplifiers but utilizes an advanced switch mode power supply, which contributes to its compact form factor and efficient power utilization.
The A2m has several additional features that make it uniquely flexible. A rear-panel switch allows the A2m to be used either as a power amplifier, with a fixed gain, or as an integrated amplifier, with a higher gain, and a convenient front panel Volume control. This allows the A2m to be used with a single line-level stereo analogue source without the need for a separate preamp. Another switch allows the A2m to be configured to turn on automatically when it detects either a standard Trigger input or an incoming audio signal.
The front panel of the A2m includes a full-sized ¼” headphone jack driven by some very special headphone circuitry. Like the headphone outputs on highly prized vintage gear, the headphone output on the A2m is powered directly from the main output amplifiers, through a pair of precision dropping resistors. This enables the A2m to power both regular low-impedance headphones and demanding high-impedance headphones with ease; a special internal jumper option allows you to route the main output power directly to the headphone output to drive low-impedance planar headphones.
Size and Weight
Dimensions 464mm x 76mm x 362mm
Weight 3.4kg
Audio Specifications
Power Output (Two Channels Driven) 50 watts RMS per channel; 20 Hz – 20 kHz; THD <0.1%; into 8 Ohms
90 watts RMS per channel; 1 kHz; THD <1%; into 4 Ohms
Power Output (headphone output; normal mode) 8 Ohms: 60 mW / channel
33 Ohms: 200 mW / channel
47 Ohms: 250 mW / channel
150 Ohms: 430 mW / channel
300 Ohms: 440 mW / channel
600 Ohms: 350 mW / channel
Power Output (headphone output; direct drive mode - requires internal jumper; USE WITH CAUTION) 8 Ohms: 50 watts/channel
33 Ohms: 12 watts/channel
47 Ohms: 8.5 watts/channel
150 Ohms: 2.6 watts/channel
300 Ohms: 1.3 watts/channel
600 Ohms: 0.6 watts/channel
Power Bandwidth (at rated power; 8 Ohm load) 20 Hz to 20 kHz (+ / – 0.07 dB)
Broad Band Frequency Response 10 Hz to 80 kHz +0/-1.8 dB
THD + noise <0.02% (A-weighted); ref rated power
Signal to Noise Ratio (8 Ohm load) >112 dB; ref rated power; (A-weighted)
Minimum Recommended Load Impedance (per channel) 4 Ohms (which equals one 4 Ohm load or two paralleled 8 Ohm loads)
Damping Factor (8 Ohm load) >500
Input Sensitivity and Gain (for rated power; 8 Ohm load) Fixed gain mode: 0.7 V / 29 dB
Variable gain mode: 0.5 V / up to 32 dB
Input Impedance 27 kOhms
Input and Output Connections
Input Connection Unbalanced (RCA); one each per channel
Speaker Output Connections Audiophile grade 5-way binding posts
Headphone output (front panel) Full sized ¼” stereo headphone jack
Trigger Trigger Input: 5 – 12 V (AC or DC); <10 mA input current required
Trigger Output: 12 VDC; can drive any load up to 120 mA.
Power Requirements
Power Requirement 115 - 230 VAC @ 50 / 60 Hz (automatically detected)
Front Panel Controls and Indicators
Standby Push button
Status LED One per channel; blue
Status LED Change to red to indicate a fault condition
Standby LED Amber
Rear Panel Controls
AC Power switch Slide switch selects between On and Auto-On modes
Gain switch Slide switch selects between Variable Gain and Fixed Gain modes
Mechanical
Protection The BasX A2m is protected against excessive operating temperature, shorted speaker connections, ground faults, and other common fault conditions
Internal Settings One pair of internal jumpers can be used to bypass the series dropping resistors to enable full output power to be routed directly to the headphone output (shipped with jumpers OFF)
