Gustard H20: power output and what it will drive

The Gustard H20 is a desktop amplifier at $929. It delivers 12.0 W into 32Ω and 1.3 W into 300Ω, which ranks it 1 of 280 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 571 of the 571 dynamic and planar headphones catalogued here. Power is published at 32Ω, 64Ω, 150Ω, 300Ω, 600Ω; the rest of the table is derived from those figures. The published figures describe the balanced output, so the single-ended jack will put out less. Output impedance is not published. Output noise is not published, so the hiss estimate cannot be run.

The manufacturer publishes 12.0 W into 32Ω, 5.4 W into 64Ω, 2.7 W into 150Ω, 1.3 W into 300Ω, 670 mW into 600Ω. Everything else in the table above is worked out from those figures, and this table says which is which.

The published figures describe the balanced output. A single-ended jack on the same unit will put out less — usually about half the voltage and a quarter of the power.

Nothing here is derived: every figure in the table is either a number the maker published at that exact load or a number marked unverified. The method behind the labels is written up here.

Source: gustard.com, gustard.com.

Ordered from easiest to hardest to drive. Headroom is measured at 100 dB SPL, which is louder than almost anyone listens — a small negative number means the source still plays loud, just without reserve for peaks.

These figures come from each manufacturer's own sensitivity rating. A handful of planars — the HiFiMAN Susvara and HE-6se and the Abyss AB-1266 in particular — are widely reported to need far more than their published sensitivity implies, so treat a bare pass on those as optimistic rather than settled.

The manufacturer does not publish an output noise figure for this source, so the hiss estimate that runs on every other page here cannot be run on this one. Rather than substitute a plausible number, this page leaves the question open.

If you know the noise figure from a measurement you trust, the hiss calculator takes it directly and tells you where that noise lands in your own in-ears.

The manufacturer does not publish an output impedance for this source. That is the one number that decides whether it leaves your headphones alone or acts as a tone control, so its absence matters more than it looks: without it, nothing here can tell you how this source will behave with a multi-driver in-ear.

If you find a measured figure you trust, the checker will work out the consequence for any headphone.

Or put any two side by side in the source comparison tool, or run your own headphones through the amplifier matcher. Or see every Gustard source in the database, and how much of what this site says about them came from Gustard’s own documents.