Pioneer - SX-690 Solid state stereo amplifier

Pioneer SX-680 stereo receiver,
a vintage audio amplifier/receiver built by Pioneer in the late 1970s (around 1978-1980). Side panels made of a material that imitates black marble with white veins.
This is a classic piece from the golden era of hi‑fi, with AM/FM radio tuner, integrated amplifier of about 30 watts per channel, tone controls (bass, treble, balance), input selector, and headphone output. It is highly valued by analog audio enthusiasts for its warm sound and robust build.
Amplification
• Output power: 30 watts per channel RMS (continuous) into 8 ohms (stereo).
• Total Harmonic Distortion (THD): 0.1% (or less).
• Intermodulation distortion: Less than 0.1%.
• Damping factor: 25.
• Frequency response: 5 Hz to 100 kHz.
• Minimum speaker impedance: 4 ohms.
Inputs and sensitivity
• Input sensitivity:
• Phono (MM): 2.5 mV.
• Line (Aux, Tape): 150 mV.
• Signal-to-noise ratio (SNR):
• Phono (MM): 75 dB.
• Line: 90 dB.
• Line output: 150 mV.
Tuner
• Bands: FM and AM (MW).
• FM sensitivity: Approximately 1.9 µV (good reception).
General features
• Controls: Bass, Treble, Balance, Loudness, input selector (Phono, Aux, Tape, Tuner), high/low filter.
• Illuminated analog power meters.
• Headphone output.
• Sturdy construction with a metallic chassis and a silver-faced front panel.
Dimensions and weight
• Dimensions: 435 mm (W) × 144.5 mm (H) × 314 mm (D).
• Weight: 8.9 kg.
This receiver stands out for its warm and powerful sound for its size, ideal for vintage hi‑fi systems. It is highly valued for its Japanese build quality and its sensitive FM tuner. If you use it today, it pairs well with efficient 8-ohm speakers.
Minimal signs of use.