What is the Yamaha A-S801 and where does it sit in the lineup?
The Yamaha A-S801 is a fully integrated stereo amplifier with a built-in ESS SABRE digital-to-analog converter, positioned near the top of Yamaha's mid-tier integrated range below the more elaborate A-S1200, A-S2200, and A-S3200 flagship models. It represents the point in the catalog where Yamaha adds a genuine high-resolution DAC and USB computer audio to the traditional analog integrated formula, making it the natural anchor for a modern hi-fi system that must serve both a turntable and a laptop or streamer.
Yamaha has been building audio components since 1954, and the company carries a design philosophy it calls Natural Sound, which prioritizes tonal accuracy and low coloration rather than an exaggerated or hyped presentation. The A-S801 inherits that lineage along with the distinctive symmetrical faceplate layout, the twin analog meters absent on this model but present higher up the range, and the emphasis on solid mechanical construction that has defined the A-S series for years.
Amplification Topology and Circuit Design
How does the A-S801 amplifier stage work?
The A-S801 uses a conventional class AB power amplifier topology built around a fully discrete output stage, which means the signal-handling devices are individual transistors rather than integrated modules. Class AB is chosen because it keeps the output devices biased into partial conduction, eliminating the crossover distortion that plagues pure class B while avoiding the enormous heat and inefficiency of pure class A. The practical payoff is high output with clean behavior across the audible band, reflected in a rated 100 watts per channel into 8 ohms from 20 Hz to 20 kHz at just 0.019% total harmonic distortion with both channels driven.
Yamaha applies its ToP-ART concept (Total Purity Audio Reproduction Technology) here, which is the company's term for a set of construction principles aimed at signal purity: short and symmetrical signal paths, low-impedance connections, and a rigid mechanical chassis to keep sensitive circuitry stable. The company also implements a fully balanced internal signal path in its designs to reject common-mode noise picked up along the way, so that hum and interference cancel rather than accumulate.
What does the damping factor of 240 tell you about speaker control?
The damping factor of 240 or greater into 8 ohms at 1 kHz tells you the amplifier presents a very low output impedance relative to the speaker load, which translates to firm control over driver motion. Damping factor is the ratio of the load impedance to the amplifier's output impedance, so a figure of 240 means the amplifier's output impedance is roughly one two-hundred-fortieth of 8 ohms. In audible terms, a high damping factor lets the amplifier quickly arrest the residual motion of a woofer cone after the signal stops, tightening bass definition and reducing overhang. This is particularly valuable with larger, high-excursion drivers whose momentum can otherwise blur transients.
How much real-world power does the A-S801 deliver into different loads?
The A-S801 delivers 100 watts per channel into 8 ohms and 120 watts per channel into 4 ohms, which shows the amplifier increases its output as speaker impedance drops. An ideal voltage source would double its power when impedance halves; the increase from 100 to 120 watts is more modest, indicating the power supply and output stage current delivery are substantial but not unlimited. Note that the 4 ohm figure is rated at 1 kHz with 0.038% THD, a single-frequency measurement, while the 8 ohm figure is the more demanding full-bandwidth rating from 20 Hz to 20 kHz. On top of the continuous rating, the amplifier is specified for 130 watts of dynamic power into 8 ohms, meaning it can briefly exceed its continuous rating on short musical peaks by drawing on stored energy in the power supply. That headroom is what gives music its sense of effortless dynamic swing.
Power Supply and Internal Construction
Why does the power supply matter so much in this amplifier?
The power supply matters because every watt the amplifier delivers to your speakers must first be stored and supplied cleanly by it, and the ability to service dynamic peaks like the specified 130 watts depends entirely on the supply's reserve. Yamaha equips the A-S series with a substantial power transformer and large filter capacitance to act as an energy reservoir, so that transient current demands do not sag the rail voltages and compress the sound. A stiff supply also keeps the noise floor low, which supports the quoted signal-to-noise ratio of 99 dB on the CD input with a 200 mV input and shorted terminals.
How is the chassis built and why does the construction affect sound?
The A-S801 is built on a rigid chassis weighing 13.1 kg within dimensions of 435 by 157 by 396 mm, and that mass and rigidity are functional rather than cosmetic. Mechanical vibration from the transformer, from the room, and from the speakers themselves can modulate sensitive circuit elements and introduce microphonic coloration. A heavy, well-braced chassis raises the resonant frequency of the enclosure and damps stray energy, keeping the circuit boards mechanically quiet. Yamaha's practice of anti-resonance construction, including thick side panels and carefully positioned feet, is aimed at exactly this. The left-right symmetrical internal layout also serves signal integrity by keeping the two channels' paths equal in length and impedance, which supports consistent imaging.
Digital Section and DAC
What DAC does the A-S801 use and what formats does it support?
The A-S801 uses the ESS SABRE ES9010K2M digital-to-analog converter, which supports PCM up to 384 kHz and 32-bit resolution and DSD up to 11.2 MHz over its USB input. The ESS SABRE family is known for its high dynamic range and low distortion, achieved through a Hyperstream modulator architecture and a proprietary jitter-reduction system inside the chip. Jitter is timing error in the digital clock, and even small amounts smear fine detail and harm imaging, so on-chip jitter suppression is a meaningful contributor to clean high-resolution playback. Support for DSD at 11.2 MHz means you can play quad-rate DSD files natively, and 384 kHz PCM handling covers essentially every commercially available high-resolution download.
How does the USB input differ from the optical and coaxial inputs?
The USB Type B input differs from the optical and coaxial inputs because it connects directly to a computer and is the only input that carries the full range of high-resolution PCM and native DSD to the DAC. The single optical and single coaxial S/PDIF inputs are designed for source components like disc players, televisions, and streamers, and they operate within the standard limits of the S/PDIF interface rather than the higher ceilings of the asynchronous USB path. Asynchronous USB is significant because the amplifier's own clock governs timing rather than the computer's, which reduces jitter transferred from a noisy host machine. For the cleanest results from a PC or Mac, the USB input is the preferred connection.
Analog Inputs, Phono, and System Integration
Does the A-S801 have a phono stage and what cartridges does it support?
Yes, the A-S801 includes a built-in moving magnet phono stage, so you can connect a turntable fitted with a moving magnet cartridge directly without an external preamplifier. The phono input applies the RIAA equalization curve, which reverses the frequency shaping applied during record cutting to restore flat response, and it provides the gain needed to bring a moving magnet cartridge's low output up to line level. Moving coil cartridges, which have much lower output, would require an additional step-up device since this stage is optimized for moving magnet loading.
What analog and digital connections does the A-S801 provide?
The A-S801 provides five line-level analog inputs plus the moving magnet phono input on the analog side, and a USB Type B, one optical, and one coaxial input on the digital side. That combination lets you integrate a wide array of sources, from a CD player and a tuner to a network streamer and a computer, all within a single unit. This breadth is a large part of why the model works as a system hub rather than merely a power amplifier with a volume control.
Can the A-S801 drive two pairs of speakers, and is there a subwoofer output?
The A-S801 provides Speaker A and Speaker B terminals so it can drive two pairs of speakers, but it does not include a dedicated subwoofer output. The A and B terminals allow you to run a second pair in another part of the room or to A/B compare two sets of speakers, and depending on selection they can be run individually or together. Because there is no subwoofer preout, adding a powered subwoofer requires either a subwoofer with speaker-level inputs or taking the signal from a second speaker set, so it is worth planning your low-frequency strategy around that limitation if a subwoofer is essential to your system.
What does the headphone jack offer for private listening?
The A-S801 includes a front-panel headphone jack for private listening, driven from the amplifier's internal circuitry rather than a separate afterthought output. This lets you enjoy the same source selection and volume control for headphone sessions without adding a standalone headphone amplifier for casual use.
What is Pure Direct mode and when should you use it?
Pure Direct is a mode that shortens the signal path by bypassing the tone controls, balance, and other processing circuitry so the signal travels the most direct route from input to output. You should use it when you want the least possible coloration from source material that is already well balanced, since removing those stages reduces the number of components the signal passes through and lowers the opportunity for added noise or phase shift. When a recording benefits from tonal adjustment, you can switch back to the standard path and use the bass and treble controls.
Interpreting the Measurements
What does the frequency response specification actually mean here?
The frequency response of 10 Hz to 100 kHz at plus 0 and minus 3.0 dB on the CD input means the amplifier passes everything from deep subsonic territory to well beyond human hearing with no more than a 3.0 dB rolloff at the extremes. Extending flat response far above 20 kHz is not about hearing those frequencies directly but about ensuring the amplifier is not straining anywhere within the audible band, which keeps phase behavior linear and transients accurate through the treble. The wide bandwidth is a hallmark of a design with generous headroom rather than one tuned right at the edge of audibility.
How should you read the distortion and signal-to-noise figures together?
You should read the 0.019% THD and the 99 dB signal-to-noise ratio together as a picture of a low-coloration, quiet amplifier. The 0.019% figure, measured across the full 20 Hz to 20 kHz band at 50 watts into 8 ohms, indicates that harmonic distortion products sit far below the level where they would be audible on music. The 99 dB signal-to-noise ratio, referenced to the CD input, indicates the desired signal sits about that far above the residual noise floor, so quiet passages remain clean and free of audible hiss or hum. Together they describe an amplifier engineered to get out of the way of the recording, consistent with Yamaha's Natural Sound intent.
