EPZ TP50: power output and what it will drive

The EPZ TP50 is an USB dongle at $210. It delivers 121 mW into 32Ω and 13 mW into 300Ω, which ranks it 200 of 280 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 496 of the 571 dynamic and planar headphones catalogued here, enough but not generous on 60, only marginal on 9 and not enough power for 6. Power is published at 32Ω; the rest of the table is derived from those figures. Output impedance is not published.

The manufacturer publishes 121 mW into 32Ω. Everything else in the table above is worked out from those figures, and this table says which is which.

The balanced output is rated separately: 240 mW into 32Ω through the 4.4mm jack.

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: epzaudio.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 1.0 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 18 dB SPL, which you will hear between tracks and in quiet passages.

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 EPZ source in the database, and how much of what this site says about them came from EPZ’s own documents.