Icon Audio Stereo 40 MkIV Integrated KT88 Amplifier

Icon Audio Stereo 40 MkIV Integrated KT88 Amplifier

Our best valve amplifier just got better!

KT88 or 6550 valves
Headphone Socket
«Easy Bias» Meter
50+50 Watts rms*
30+30 Watts Triode
Remote Control
Record Loop
Valve and capacitor upgrade available, please enquire with us.

Exceptional performance at a modest price!

The Stereo 40 MKI was our first model in 2001 and has always been a special product to us. Since that time we have substantially improved it over the years.

In its latest guise, the MK IV has several upgrades making it exceptional value.

 Headphone Socket.

Exceptional quality is provided by using separate HQ windings of the output transformer. Not attenuation is used to give a very open sound. Suitable for 8 to 500 Ohms. Giving greater flexibility of use.

Improved Power Supply.

In conjunction with our re-designed output transformers, the Ultralinear Power is now over 50 Watts. This gives greater instantaneous power available for heavy transients, and a more solid bass.

More Triode Power.

We know that majority of customers use the Triode Facility most of the time. The Triode power is now 30 Watts enabling use of all but the most inefficient speakers.

Re designed driver circuit.

Using a “cascode” configuration for the first stage enables us to use the venerable 6SN7 valve for all the driver circuit functions. This gives better definition whilst improving the frequency response at lower volumes. This also simplifies valve replacement as the amplifier only uses two valve types.


The Stereo 40 MK IV is packed with high end features:

 Choke Regulated Power Supply

Working in conjunction with the smoothing capacitors the large choke gives super-smooth power regulation for a silent background.

Tertiary Transformers have an extra (third) winding which reduces distortion, using less global feedback. We believe our large handmade output transformers to be amongst the finest available. They are more expensive and difficult to make, but worth the effort.

Low Feedback Too much feedback can spoil the sound of an amplifier. We only use a small amount in the Stereo 40 MK IV.

GEC KT88 and U.S. 6550 valves

Considered by many to be the finest Beam Pentode valve ever created, efficient, easy to drive with low distortion the Stereo 40 MK IV is designed to get the best out of this valve in big dynamics and micro detail. The American 6550 is a similar alternative.

Ultralinear or Triode?

For sixty years hi fi fans have argued which sound is better. With the Stereo 40 IV you have the choice of both at the flick of a switch. It is like having two amplifiers in one! Most hi fi fans prefer the sound of triode operation.

6SN7 (CV181)

This vintage 1941 forerunner of the miniature ECC series has a more “vivid” sound and balances well with the modern KT88. Our CV181 version comes as standard.

Remote Control

Useful to get exactly the right volume in your listening chair position. Allows fine adjustment of the right sound level.

Plenty of Power

50 watts of power is enough to fill a medium to large room with a high volume of musical excellence.

We can offer a range of upgrades including Shuguang “Treasure” valves and Russian types. As well as the superb Mundorf “silver/gold in oil” capacitors. Ask us for a quote.