Icon Audio Stereo 40 MkIV KT88

Icon Audio Stereo 40 MkIV KT88


The Icon Audio ST40 MKI was Icons first design in 2001 and has always been a special product to us. Since that time they have substantially improved it over the years and its latest guise, the MK IV has several improvements making it exceptional value.

SKU: 926c11cc055d


Headphone Socket.

Following customer feedback the new model now has this feature. 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.

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)

More relaxed than their miniature cousins, these larger driver valves are the best in their class for their musical sound and longer life. Try our new David Shaw types or new production and vintage USA/Russian types.

Remote Control

Useful to get exactly the right volume in your listening 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 Jensen “oil in paper” capacitors. Ask us for a quote.

Specifications and Features

Comprehensive manual supplied
Remote control: HQ ALPS motorised volume pot
All hand wired point to point
Class A, all Triode front end
Output circuit Ultralinear or Triode switchable
4x KT88 matched for best performance
4x 6SN7 for first stage valve and phase splitter
Standby switch to save valve life and power
2x 50w per channel Ultralinear output
2x 30 Watts in Triode mode
Signal to noise level -90db
Freq response better than 20hz-20kHz +0 – 1db
Power bandwidth 30Hz-30kHz -3 dB
Total harmonic distortion 0.2% at full output
Suitable for 4 to 16ohm loudspeakers
Supplied with valve cover.
Choke regulated power supply
Solen audio caps, or Jensen copper foil in paper and oil
Silver PTFE audio cable
Custom hand wound Tertiary output transformers
Gold plated Input & speaker terminals
Four line inputs: CD, Tuner, Aux plus Tape
Tape monitor circuit with ‘Record Out’
Input sensitivity 250mv.(high). 800mv (low).
Power requirement 230-240volts (117v adjustable)
76 Watts standby, 140 W Min, 240 W
39cmW, 41D, 23H, 22kg (allow for ventilation)


It would be our pleasure to demonstrate this product in store for you, contact us to arrange an appointment

Available for UK & EU shipping, please get in touch to arrange EU shipping

All new products come with a manufactures warranty

Please contact us if you own Icon gear that you’d like to sell, or that would benefit from service / repair

Additional information



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