Generic CX31993 dongles: power output and what it will drive

The Generic CX31993 dongles is a USB dongle at $12. It delivers 60 mW into 32Ω and 9.0 mW into 300Ω, which ranks it 49 of 53 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 226 of the 310 dynamic and planar headphones catalogued here, enough but not generous on 78, only marginal on 4 and not enough power for 2. A whole family of cheap dongles built on this chip. Often noisy with a high output impedance — risky with multi-BA IEMs.

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

This one hisses. With the most sensitive in-ears in the database its own noise lands around 33 dB SPL, which you will hear between tracks and in quiet passages.

At 1.5Ω output impedance, the one-eighth rule says this source suits headphones of 12.0Ω 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.