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 245 of 280 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 446 of the 567 dynamic and planar headphones catalogued here, enough but not generous on 101, only marginal on 6 and not enough power for 14. No manufacturer stands behind these. They are built on a Conexant/Synaptics CX31993 chip whose datasheet is behind an NDA, sold under dozens of names, and the specifications printed on marketplace listings are seller copy. Treat every number here as an indication of the type, not of the dongle in your hand.

Nothing in the table above could be traced to a document this manufacturer publishes. The figures come from the material this database was first built from — independent measurement and reviewer reports — and every one of them is labelled unverified for that reason. They are being re-sourced one model at a time, and this page will change when the maker publishes something or a document turns up.

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.

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 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.

That noise figure has not been traced to a document from the maker, so the levels below are as good as the number they start from.

This one hisses. With the most sensitive in-ears in the database its own noise lands around 39 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. 51 of the 567 models here fall below that. Most of them are multi-driver in-ears, and the mismatch tilts the frequency response audibly rather than subtly.

That output impedance has not been traced to a document from the maker, so the count above is only as good as the number it starts from.

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.

Nothing cheaper in this database does everything the Generic CX31993 dongles does. Of the 280 sources here, not one at a lower price will reach 100 dB on every headphone it reaches. That is a plain result and it is not the usual one — most of the catalogue has something cheaper that matches it.

It is worth knowing how that was counted. The maker publishes no output impedance and no noise figure for this one, and an axis nobody published is an axis nothing had to match. The result above rests on the figures that exist.

This counts a headphone output and nothing else. Inputs, converters, microphone preamps, balanced outputs, the volume control, the case and the warranty are all outside it, and any of them can be the reason to buy the dearer box. What the count does say is that the three numbers a maker can be held to do not separate them.

Worked out in advance against its closest rivals: vs Apple USB-C dongle (EU) · vs Apple USB-C dongle (US). Each of those pages lists the headphones that tell the two apart.

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