The Yamaha A-S801 is an integrated amplifier built around a traditional class AB topology combined with a modern onboard digital section. It marries a preamplifier stage and a power amplifier stage in a single chassis, so a single unit handles source switching, volume control, and speaker drive. The class AB design allows the output devices to operate efficiently at low levels while retaining the linearity and current delivery needed for demanding musical passages, which is the enduring appeal of this architecture for two channel listening.
How does the internal layout contribute to performance?
The A-S801 uses a symmetrical internal layout intended to keep left and right signal paths as balanced and short as possible. Yamaha routes the two channels along mirror image paths so that the electrical characteristics of each channel match closely, which reduces channel imbalance and helps preserve stereo imaging. Keeping the paths short also limits opportunities for noise pickup and signal degradation, and separating the power supply and high current sections from the sensitive input stages minimizes interference between them.
Why does the chassis feel so heavy for its size?
At 12.1 kg in a chassis measuring 435 x 152 x 387 mm, the A-S801 carries most of its mass in the power supply and heat management hardware. The weight comes primarily from the power transformer, the filter capacitance, and the heat sinks bonded to the output transistors. A rigid, well braced chassis also resists vibration, which matters because mechanical resonance can modulate the audio signal in subtle ways. The compact footprint keeps it manageable on a standard rack shelf while still delivering serious internal hardware.
Power Supply and Output Stage
How much power does the A-S801 actually deliver?
The A-S801 is rated at 100 watts per channel into 8 ohms across the full 20 Hz to 20 kHz band at 0.019% THD with both channels driven, and 120 watts per channel into 6 ohms across the same band at 0.038% THD with both channels driven. The full bandwidth 8 ohm figure is the more conservative and meaningful specification because it is measured across the entire audible range with both channels working, rather than at a single frequency. The increase to 120 watts into 6 ohms shows the amplifier can deliver more current into lower impedance loads, a sign of a supply and output stage with real headroom.
What does the dynamic power rating tell us?
The dynamic power rating of 130 watts per channel into 8 ohms reflects the amplifier's ability to deliver short term bursts above its continuous rating. Music is not a steady tone; it contains transient peaks such as drum strikes and orchestral swells that demand momentary current far beyond the average level. The gap between the 100 watt continuous figure and the 130 watt dynamic figure indicates the power supply stores enough energy to supply these peaks without sagging. In practice this translates to a sense of effortlessness on dynamic material.
Why does the damping factor matter?
The A-S801 specifies a damping factor of 240 or greater into 8 ohms at 1 kHz, which describes how firmly the amplifier controls the speaker's motion. Damping factor is the ratio of the load impedance to the amplifier's output impedance, so a high number means very low output impedance. This lets the amplifier act as a strong brake on the woofer cone, halting its motion quickly after the signal stops rather than allowing it to overshoot and ring. The audible result is tighter, more articulate bass and cleaner transitions, particularly with speakers that have loosely damped low frequency drivers.
How clean is the amplifier's output?
The A-S801 posts a total harmonic distortion figure of 0.019% measured at 50 watts into 8 ohms across the 20 Hz to 20 kHz band, and a signal-to-noise ratio of 99 dB referenced to the CD input with a 200 mV input and shorted terminals. The THD figure is very low and, importantly, it holds across the full audible bandwidth rather than only at a convenient midband frequency, which is the harder test to pass. The 99 dB signal-to-noise ratio means the noise floor sits well below the music, so quiet passages remain quiet and low level detail is not masked by hiss.
How wide is the frequency response?
The A-S801 measures 10 Hz to 100 kHz within +0 and -3.0 dB through the CD input. Extending well below the audible bottom limit and far above 20 kHz ensures that the amplifier introduces no audible rolloff or phase anomalies within the range we can hear. A response that reaches to 100 kHz also indicates a fast, wide bandwidth design that handles the leading edges of transients accurately, since steep signal edges contain high frequency energy that a narrower amplifier would smear.
The Digital Section and DAC
What DAC does the A-S801 use?
The A-S801 incorporates an ESS SABRE ES9010K2M digital to analog converter, a well regarded chip from ESS Technology's SABRE family. This converter uses a hyperstream modulator and a jitter elimination design intended to reduce timing errors that can blur digital audio. Building a capable DAC directly into the amplifier means you can connect digital sources without needing a separate outboard converter, and it keeps the digital to analog conversion within the same carefully grounded chassis as the analog stages.
What digital formats can it handle?
Through its USB Type B input the A-S801 accepts PCM up to 384 kHz and 32-bit, and native DSD up to 5.6 MHz (DSD128). These are high resolution capabilities that comfortably exceed standard CD quality and cover essentially all commercially available high resolution downloads and streams. The 384 kHz/32-bit PCM ceiling accommodates the highest sample rate files most listeners will encounter, while native DSD support up to 5.6 MHz means double rate DSD128 material can be played back without conversion to PCM first.
What digital inputs are available?
The A-S801 provides three digital inputs: a USB Type B port, one optical input, and one coaxial input. The USB Type B connection is the pathway to a computer and the one that unlocks the full 384 kHz/32-bit PCM and 5.6 MHz DSD capability of the internal DAC. The optical and coaxial inputs accept S/PDIF signals from sources such as disc players, network streamers, or televisions, with the coaxial connection generally preferred for its electrical robustness and the optical connection valued for its inherent galvanic isolation between components.
Can the digital section be bypassed?
Yes, the A-S801 offers a pure direct function that shortens the signal path by bypassing the tone and balance circuitry for the most faithful reproduction of the source. When engaged, this routes the signal through the fewest possible active stages, removing the tone control network from the path. For listeners who want to hear the recording exactly as mastered, this mode strips away any coloration the tone controls might introduce, letting the source and the power amplifier do the work with minimal intervention.
Analog Inputs and the Phono Stage
How many analog inputs does it have?
The A-S801 offers five line level analog inputs plus a dedicated moving magnet phono input. The five line inputs give you generous capacity to connect analog sources such as a network player, a tuner, a disc player, or a secondary DAC, all through standard RCA connections. Having this many line inputs means the digital section does not crowd out traditional analog gear, so the amplifier serves as the central hub for a mixed system of old and new sources.
Can I connect a turntable directly?
Yes, the dedicated moving magnet phono input lets you connect a turntable fitted with a moving magnet cartridge without an external phono preamplifier. A phono stage performs two essential jobs: it applies substantial gain to bring the tiny cartridge output up to line level, and it applies the RIAA equalization curve that reverses the frequency shaping used when records are cut. Because this stage handles extremely low level signals, integrating it into the amplifier keeps the delicate cartridge signal short and shielded before it is amplified.
Outputs, Controls, and System Integration
What speaker outputs are provided?
The A-S801 features two sets of speaker outputs, labeled Speaker A and Speaker B. These allow you to connect two pairs of speakers and select between them, drive them together, or use the second pair to feed speakers in another room. The dual outputs also make A/B comparison of two speaker pairs straightforward and support biwiring arrangements when you want to run separate cable runs to a speaker's high and low frequency terminals.
Is there a subwoofer output?
Yes, the A-S801 includes a subwoofer output that lets you add a powered subwoofer to extend low frequency response. This line level output feeds a subwoofer's own amplifier, so you can supplement the main speakers with dedicated bass reinforcement. This is particularly useful with compact stand mount speakers that cannot reproduce the deepest octaves on their own, allowing a two channel system to reach fuller low end without changing the main speakers.
Is there a headphone output?
Yes, the A-S801 provides a front panel headphone jack for private listening. This lets you drive a pair of headphones directly from the amplifier without disturbing others, drawing on the same source selection and volume control as the main system. It makes the amplifier a complete listening solution for late night sessions or focused critical listening away from the speakers.
What tone and control features are on the front panel?
The A-S801 includes bass and treble tone controls, a balance control, a loudness contour, and the input selector and volume for everyday operation. The tone controls let you adjust the low and high frequency balance to taste or to compensate for room and recording characteristics, while the balance control corrects for off center seating or channel level differences. The loudness contour boosts the frequency extremes at low listening levels to counteract the ear's reduced sensitivity to bass and treble when the volume is quiet, and all of these can be taken out of the path with the pure direct mode when you want the untouched signal.
Who is the A-S801 best suited for?
The A-S801 suits the enthusiast who wants a single, substantial component that combines a capable class AB power amplifier, a high resolution ESS SABRE DAC, and a moving magnet phono stage in one chassis. With 100 watts per channel into 8 ohms, a damping factor of 240 or greater, three digital inputs, five line inputs, phono, dual speaker outputs, a subwoofer output, and a headphone jack, it functions as the core of a serious two channel system that can bridge vinyl, digital files, and traditional line sources. It is a mature, well specified integrated amplifier for the listener who values flexibility and measured performance in equal measure.
