Quad 405 - Power Amplifiers - Good w/ Original Box

Why This One

• Good condition — clearly used but works as it should
• Fully tested — all applicable functions verified working
• Patented current-dumping circuit delivers 100W per channel with under 0.01% THD.
• Comes in its original box — a rare find for a classic amplifier of this age.

Condition: Good

This Quad 405 is a good-condition power amplifier. It has passed our 8-point functional test, with 2 item(s) not applicable to this unit. Please review all photos carefully, as they provide an accurate representation of the cosmetic condition of the product.

What's Included

• Quad 405
• Original Box

About This Model

The Quad 405 is a stereo power amplifier built around Quad's patented current-dumping topology — an elegant circuit combining a low-powered Class A stage that maintains continuous speaker control with a high-powered section that cuts in only when high-amplitude signals demand it. The result is 100 watts per channel into 8-ohm loads with vanishingly low distortion: less than 0.01% THD at 1 kHz and less than 0.05% at 10 kHz, alongside a signal-to-noise ratio of 95 dB. Frequency response is flat across the audible range, rolling off only at the extremes. The amplifier is unconditionally stable with speaker loads between 4 Ω and 16 Ω and requires no internal adjustments. An internal power limiter can reduce output to 50 watts for use with lower-power speakers, including Quad's own electrostatic models. Connections are via a 4-pin DIN input and spring-loaded speaker terminals.

A great opportunity to own a Quad 405 at this price point.