Esoteric F-01/PS-01F

If you are the kind of person who judges amplifiers on a power-per-pound basis, Esoteric's range-topping F-01 integrated is in trouble.

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• Integrated amplifier/power supply

• £27,500

After all, when a 30-watts-per-channel integrated stereo amplifier costs much the same as a decent second-hand car, questions need to be asked. Fortunately for Esoteric, the F-01 has all the answers.

Why such a low output? The F-01 (£22,000) has a Class-A circuit, and with that comes the promise of great sound quality and the curse of lots of heat. In such a design, the greater the power output, the more heat the amp will produce, so there is always a balance the engineers have to strike.

Esoteric configures the very similar F-02 integrated amplifier (£20,000) in Class A/B, and that has a claimed power output of 120W into an 8-ohm load and uses half the power at idle when doing so (110W vs 215W for the F-01).

While integrated-amplifier designs are usually seen as some sort of compromise compared with separate pre/power alternatives, given the price it is fair to assume that isn't the case here. The F-01's preamp circuitry design borrows heavily from the company’s range-topping two-box Grandioso C1X preamplifier (£47,500), which is a great starting point.

Aside from the usual embellishments we would expect from a product at this level, such as the use of top-grade components, generous power supply arrangements and carefully considered circuit layouts, the unusual thing here is that the F-01 preamp section operates with its voltage rails set far higher than in conventional designs. Such an approach is claimed to improve dynamics and the signal-to-noise ratio.

It has a dedicated feed from the power supply to minimise unwanted interactions between the various sections in the amplifier. While you would think that was the end of it, Esoteric has other ideas; the F-01 is upgradeable with the optional PS-O1F outboard power supply (£5500), and we include it as part of this test.