PS Audio has introduced the PMG Signature S200 and S400, a pair of stereo power amplifiers based on the same Signature topology used in the company’s M400 and M800 monoblocks. Both models are assembled by hand in Boulder, Colorado, and offered with black or silver finishes.
Two power levels for different systems
The PMG Signature S400 is the more powerful of the two amplifiers, delivering 200 watts per channel into 8 ohms and 400 watts per channel into 4 ohms. It combines two 200-watt Signature amplification channels within a single chassis.
The S200 is rated at 100 watts per channel into 8 ohms, rising to 200 watts per channel into 4 ohms. PS Audio positions it for smaller rooms, more efficient loudspeakers and systems that do not require the S400’s additional output capability.
Class A operating range is another point of distinction. The S400 supplies its first 5 watts per channel in Class A, while the lower-powered S200 extends Class A operation to the first 10 watts per channel. This gives buyers a choice between greater maximum power and a broader initial Class A range.
Signature topology and wide-bandwidth design
Both stereo power amplifiers were designed by Darren Myers and developed by Bob Stadtherr. Their circuitry is derived from PS Audio’s PMG Signature platform, which also underpins the company’s M400 and M800 monoblock amplifiers.
According to PS Audio, the output stages employ very low negative feedback and achieve a bandwidth greater than 500 kHz. The specified slew rate exceeds 200 volts per microsecond. These figures describe the circuit’s ability to respond rapidly to changing signals and maintain phase behavior beyond the audible frequency range rather than an intention to reproduce ultrasonic music content.
Typical total harmonic distortion is stated at less than 0.002 percent from 20 Hz to 20 kHz when producing 1 watt into an 8-ohm load. Both models provide 26.2 dB of gain, although their input sensitivity differs: 2 volts for the S400 and 1.4 volts for the S200.
Active power architecture in a shared chassis
PS Audio has equipped both amplifiers with an active power-supply architecture instead of relying solely on the conventional combination of a passive transformer, rectifier and storage capacitors. The company says this approach enables the supply to maintain more consistent output as current demand changes.
That design is particularly relevant in a stereo amplifier, where both channels occupy the same enclosure and share the power-supply system. PS Audio says the active architecture is intended to reduce the extent to which heavy demand from one channel affects the other during demanding musical passages.
The single-chassis format also differentiates the S200 and S400 from the M400 and M800 monoblocks. Those products house each amplification channel separately, whereas the new stereo models package a pair of Signature channels together.
Balanced inputs and bi-wiring support
Connection options are identical across the two models. Each amplifier includes balanced XLR and unbalanced RCA inputs, allowing it to work with a range of preamplifiers and source components.
Two sets of silver-plated loudspeaker binding posts are provided for each channel. This arrangement supports bi-wiring without requiring both cable runs to share a single pair of terminals. PS Audio has also included 12-volt trigger input and output connections for coordinated power control within a larger audio system.
The PMG Signature S200 and S400 are available in black or silver.
With two output ratings, different Class A operating ranges and the same core Signature platform, the S200 and S400 extend PS Audio’s latest amplifier architecture to listeners seeking a stereo power amplifier rather than separate monoblocks.
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