The Icon Audio Stereo 40 is one of the brand’s most acclaimed valve amplifiers — refined in the MkIV version in terms of power supply, driver circuit and power. It runs on KT88 valves (6550 operation is possible) and offers 50 W per channel in ultra-linear mode and 30 W in triode mode, switched with a single flick of a switch.
The design is based on completely hand-wired point-to-point assembly, with no printed circuit boards. The redesigned driver stage uses a 6SN7 valve in a cascode arrangement, and a large choke working with filter capacitors provides exceptionally smooth power regulation. Output transformers with an additional (tertiary) winding reduce distortion with minimal feedback.
The Stereo 40 MkIV features a high-quality headphone output (separate transformer windings, 8–500 Ω compatibility), an „easy bias” meter, a standby mode that extends valve life, a recording loop and a remote control with a motorised ALPS potentiometer. 50 W of power easily fills a medium or large room.
| Output power | 50 W (ultra-linear) / 30 W (triode) per channel |
| Output valves | 4× KT88 (or 6550) |
| Driver valves | 4× 6SN7 (CV181) |
| Inputs | 4× (CD, Tuner, Aux, Tape) + recording loop |
| Input sensitivity | 250 mV (high) / 800 mV (low) |
| Signal-to-noise ratio | −90 dB |
| Frequency response | 20 Hz – 20 kHz (+0 / −1 dB); power bandwidth 30 Hz – 30 kHz (−3 dB) |
| THD distortion | 0.2% at full power |
| Speaker impedance | 4, 8, 16 Ω |
| Power supply | 230–240 V; consumption 140–240 W |
| Dimensions (W × D × H) | 390 × 410 × 230 mm |
| Weight | 23 kg |
Integrated valve amplifier on KT88 valves — 50 W ultra-linear or 30 W in triode mode. Hand-wired point-to-point, headphone output and remote. Icon Audio's flagship design.
