Accuphase A-300 Class-A Monophonic Power Amplifier

Accuphase A-300 Class A Monophonic Power Amplifier

One monoblock, 20 parallel MOSFETs, and true Class A power built to drive any loudspeaker without compromise.

A Monoblock Built for a Fiftieth Anniversary

Accuphase created the A-300 to mark fifty years of amplifier design, and it shows in every part of the circuit. This is a monophonic power amplifier, meaning each unit drives a single channel, so a full stereo system requires a pair. It delivers 125 watts into 8 ohms, and that figure climbs as the load gets harder to drive: 250 watts into 4 ohms, 500 watts into 2 ohms, and a full 1,000 watts into 1 ohm. Most amplifiers lose composure as impedance drops. The A-300 was engineered to do the opposite, doubling its output every time the load halves, which tells you the power supply and output stage were built with genuinely difficult speaker loads in mind rather than a spec sheet number.

What Class A Actually Means Here

Class A operation keeps the output transistors conducting current at all times, even when no music is playing, rather than switching on and off with the signal like a typical Class AB design. That constant conduction eliminates crossover distortion, the small discontinuity that occurs whenever an amplifier hands off between output devices. The tradeoff is heat. Class A amplifiers run warm because they are always working, and the A-300 is no exception. In exchange, you get a smoothness through the midrange and treble that switching designs struggle to match, particularly on acoustic instruments and vocals where the ear is most sensitive to distortion.

Twenty Parallel Output Devices

Inside the A-300, Accuphase uses twenty push and pull power MOSFETs arranged in parallel, split across two power amplification modules. Running that many devices in parallel lowers the effective output impedance of the amplifier and spreads the current load across more silicon, which reduces stress on any single device and improves linearity at high output. Accuphase states this configuration improves performance by roughly 25 percent over its earlier designs. The signal input section is fully discrete, built from an instrumentation amplifier topology that balances impedance on the positive and negative sides of the circuit, which is a deliberate choice to reject external noise before it ever reaches the output stage.

Damping Factor and Balanced Remote Sensing

The A-300 carries a damping factor of 1,000 or greater. Damping factor describes how tightly an amplifier controls a speaker cone after a signal ends, essentially how well it can stop a woofer from moving on its own momentum. A high damping factor means tighter, more controlled bass and a more accurate stop on transients. Accuphase reinforces this with Balanced Remote Sensing, which feeds the ground reference back from the point closest to the speaker terminal rather than from inside the amplifier chassis, further tightening control over the connected loudspeaker regardless of cable length.

Power Supply, Noise Floor, and Build

A large toroidal transformer and 100,000 microfarads of filtering capacitance sit behind the output stage, providing the reserve current the A-300 needs to sustain those short bursts of high current into low impedance loads. Accuphase also uses a current feedback amplification topology, which keeps the frequency response essentially flat even as the gain switch is changed, and a Double MCS circuit, which places the voltage amplification stage in a parallel layout to reduce the noise floor by roughly 30 percent. The result is a signal to noise ratio of 130 dB at maximum gain and 135 dB when the gain is reduced to minus 12 dB, among the quietest specifications in the monoblock category. The chassis itself uses an aluminum top plate, high carbon cast iron insulator feet for vibration damping, and large speaker terminals wired directly to the protection circuitry rather than through a switch.

How It Compares to the Accuphase A-80

Buyers weighing the A-300 often ask how it stacks up against the Accuphase A-80, which uses closely related circuitry in a single stereo chassis rather than a pair of monoblocks. The A-80 is the more practical choice for a rack with limited space or a budget closer to a single high performance stereo amplifier, and it shares the same current feedback topology and balanced remote sensing. The A-300, run as a true monoblock pair, isolates each channel's power supply and output stage completely from the other, which removes any possibility of channel interaction and allows for a bridged or bi-amped configuration the A-80 cannot match. Listeners moving from an A-80 to a pair of A-300 monoblocks generally describe a meaningful step up in bass control and dynamic headroom, not an incremental one. 

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Key Specifications:

Brand: Accuphase
Model: A-300
Category: Class A Monophonic Power Amplifier (sold individually; two units required per stereo system)
Price: $24,975.00 each
Rated Output (Normal / Bi-Amp Connection): 125 W into 8 Ω, 250 W into 4 Ω, 500 W into 2 Ω, 1,000 W into 1 Ω
Rated Output (Bridged Connection): 500 W into 8 Ω, 1,000 W into 4 Ω, 2,000 W into 2 Ω
Output Devices: 20 parallel push and pull power MOSFETs
Total Harmonic Distortion: 0.03% (4 to 16 Ω), 0.05% (2 Ω), normal connection; 0.05% bridged (4 to 16 Ω)
Intermodulation Distortion: 0.01%
Frequency Response: 20 Hz to 20 kHz (+0/−0.2 dB) at rated output; 0.5 Hz to 160 kHz (+0/−3.0 dB) at 1 W output
Damping Factor: 1,000 or greater
Input Impedance: 40 kΩ balanced, 20 kΩ unbalanced (LINE)
Input Sensitivity: 1.26 V at rated output, 0.11 V at 1 W output
Gain Settings: MAX (28 dB), −3 dB (25 dB), −6 dB (22 dB), −12 dB (16 dB)
Signal to Noise Ratio: 130 dB at MAX gain, 135 dB at −12 dB gain (A weighted, input shorted)
Power Requirements: 120V AC, 50/60 Hz (US version)
Power Consumption: 230 W idle, 270 W per IEC 62368-1, 0.3 W standby
Dimensions (W x H x D): 465 x 240 x 515 mm (18.3 x 9.4 x 20.3 in)
Weight: 46.0 kg / 101.4 lbs net; 55 kg / 122 lbs shipping

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Why Buy From All Elite Audio

All Elite Audio is an authorized Accuphase dealer, which means every A-300 we sell is sourced through Accuphase's official US distribution channel and carries full manufacturer warranty coverage. That matters with a product like this, since Accuphase warranty service is tied to the country and dealer of original purchase. Our team can walk you through gain staging, bridged and bi-amp wiring, and pairing the A-300 with the right preamplifier for your speakers, and our Timonium showroom lets you hear a pair in person before you commit.

Call: 443-402-5055
Text: 443-402-5064
Visit: 1921 York Rd, Timonium, MD 21093

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FAQ

Do I need one A-300 or two?
The A-300 is a monophonic power amplifier, which means a single unit powers only one channel. To run a full stereo system you need two A-300 units, configured as a matched left and right pair. Many buyers start with one channel and add the second later, though Accuphase recommends purchasing both at the same time so the units age and bias identically. If you are building a stereo system from scratch, budget for the pair from the start rather than treating the second unit as an optional upgrade.

Does the A-300 include a phono preamp?
No, the A-300 is a power amplifier only, with no phono stage, volume control, or input switching beyond LINE and BALANCED selection. It is meant to sit at the very end of your signal chain, after a preamplifier has already handled volume, source switching, and any phono equalization. If you're building a vinyl-based system, you'll need a separate phono preamp or a preamplifier with phono built in, such as an Accuphase C-2900 or C-3900, feeding into the A-300.

Does it come with speaker cables or interconnects?
No, the A-300 ships with only its AC power cord. You'll need your own set of interconnects, either balanced XLR or unbalanced RCA, to connect it to your preamplifier, along with a high quality speaker cable terminated for the A-300's large binding posts. Our team can recommend cable options that suit the A-300's balanced circuit design and help you select the right length for your rack layout.

How does the A-300 compare to the Accuphase A-80?
The A-80 uses closely related circuitry to the A-300 but packages both channels into a single stereo chassis rather than two monoblocks. It's the better fit if you have limited rack space or want a simpler single-box solution. The A-300, run as a true pair, gives each channel its own dedicated power supply and output stage with zero interaction between channels, and it can be bridged or bi-amped in ways the A-80 cannot. Most listeners who move from the A-80 up to a pair of A-300 monoblocks describe the difference as substantial rather than incremental, particularly in bass control and dynamic headroom.

What does damping factor mean and why is 1,000 significant?
Damping factor measures how well an amplifier controls a speaker's cone movement after a signal stops, essentially how quickly it can bring the driver to rest rather than letting it ring on its own. A damping factor of 1,000 or greater is very high, and it translates into tighter, more defined bass and cleaner transient stops, especially with speakers that have less inherent cone control on their own. Accuphase reinforces this spec with its Balanced Remote Sensing system, which senses the ground reference at the speaker terminal itself rather than inside the chassis, further tightening control regardless of your speaker cable length.

Is the A-300 actually Class A, and why does it run warm?
Yes, Accuphase specifies the A-300 as a Class A driven design, meaning its output MOSFETs conduct current continuously rather than switching on and off with the music signal. This eliminates crossover distortion and is a major contributor to the amplifier's smoothness through the midrange. The tradeoff is heat, since the output stage is always working even at idle, so the A-300 needs open ventilation and should not be placed in an enclosed cabinet without airflow. This is normal behavior for any true Class A design and not a sign of a problem.

What preamplifier should I pair with the A-300?
The A-300 has no volume control of its own, so it requires a separate preamplifier ahead of it. Accuphase's own C-2900 or C-3900 preamplifiers are a natural match, since they share the same current feedback philosophy and balanced circuit design, but the A-300 will work with any high quality preamplifier that offers balanced XLR or unbalanced RCA outputs. If you already own a preamp, bring its specifications to our showroom and we'll confirm compatibility and gain staging before you buy.

Can two A-300 units be bridged or bi-amped?
Yes. The A-300 includes an operation mode selector on the rear panel that allows two units to be configured for bridged mono operation, which roughly quadruples the available power into a single speaker, or for bi-amping, where one unit drives the high frequencies and another drives the low frequencies of a speaker with separate high and low input terminals. Bridged connection changes the rated output figures significantly, and we recommend confirming your speaker's impedance rating with our team before running a bridged configuration.

What is the difference between THD and intermodulation distortion on this spec sheet?
Total harmonic distortion measures how much an amplifier adds unwanted harmonics to a single test tone, and the A-300 is rated between 0.03 and 0.05 percent depending on the load and connection type. Intermodulation distortion measures a different kind of error, the unwanted tones created when two different frequencies interact inside the amplifier, and that figure is rated at 0.01 percent. Both numbers are excellent for a high current monoblock, but they describe different things, and a low number in one does not automatically mean the other is equally low.

Where can I buy the Accuphase A-300?
All Elite Audio is an authorized Accuphase dealer, and the A-300 is in stock and available for purchase directly through us, either online or in person at our Timonium, Maryland showroom. Buying from an authorized dealer ensures your unit carries full Accuphase manufacturer warranty coverage and was not gray-market imported from another country's distribution channel. Call 443-402-5055, text 443-402-5064, or visit us at 1921 York Rd, Timonium, MD 21093 to hear the A-300 in person and get help building a system around it.