Trilogy 931 Headphone amp – ex demonstration

Trilogy 931 Headphone amp – ex demonstration

Here, we have our demonstration example of the excellent Trilogy 931 headphone amplifier.  Condition is as new, it comes boxed with manual and power lead.

A 12 month warranty applies. New price is £895


£680 + £15 carriage



Like its bigger brother the 933, the audio circuit operates in pure single ended Class A with active constant current sources. Each channel has a single continuously biased output device. The main benefits of this topology are that the output is free from crossover distortion, and the device is held at a constant temperature.

An oversized linear power supply is implemented with a custom low flux density toroidal transformer and low ESR reservoir capacitors. This provides a low noise supply for the active circuitry with generous operating headroom.

All these elements combine to give excellent small signal resolution while maintaining good drive capability for any type of headphone.


On the CNC machined aluminium front panel a 6.3mm type B stereo jack provides the output.

There are toggles for power and input select for two stereo line inputs. A quality ALPS volume control is coupled to a beautifully weighted custom machined control knob.

The rear panel offers the user two selectable stereo inputs via high quality gold plated phono connectors and the fused IEC mains inlet.

The 931 can connect easily to any existing preamplifier or directly to two stereo sources as a standalone solution for high resolution headphone listening.

We have maintained the same painstaking attention to build quality with the 931 as with all our designs. Quality components from branded sources are used throughout. Assembly is totally by hand in our UK workshops.

The output devices dissipate enough heat to need heatsinking. An extruded off the shelf heatsink would serve here, but we chose to employ a custom CNC machined part. Semiconductors are sensitive to mechanical vibration and their operating characteristics vary with temperature.

By attaching the output devices to a high mass with low mechanical resonance and large thermal inertia, the increase in resolution more than offsets the increased manufacturing difficulty.


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