Singxer SA-1: power output and what it will drive

The Singxer SA-1 is a desktop amplifier at $699. It delivers 5.5 W into 32Ω and 785 mW into 300Ω, which ranks it 12 of 88 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 310 of the 310 dynamic and planar headphones catalogued here. Fully discrete, with output impedance that changes with the gain setting — worth knowing before pairing it with in-ears.

The manufacturer publishes 10.0 W into 16Ω, 5.5 W into 32Ω, 3.1 W into 68Ω, 2.0 W into 120Ω, 380 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.

Derivation holds output voltage steady between and beyond the published loads rather than output power, because that is what an amplifier actually does. The full method is written up here.

Source: singxer.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.

At 0.3 µV of output noise, here is where that noise lands in the five most revealing in-ears in the database.

Faint hiss with the most sensitive in-ears. Around 4 dB SPL in the worst case here — audible in a silent room, gone as soon as music plays.

At 1.4 Ω output impedance, the one-eighth rule says this source suits headphones of 11.2Ω and above. 7 of the 310 models here fall below that, mostly multi-driver in-ears, where the mismatch tilts the frequency response audibly rather than subtly.

The rule is a rule of thumb, not physics: a source impedance below one eighth of the headphone's keeps the interaction under about 1 dB. The checker works it out for any pair.

Or put any two side by side in the source comparison tool, or run your own headphones through the amplifier matcher.