361mW in a Dongle: What Can It Really Drive? KEYSION 02, Measured

The role of 02 in the KEYSION series is clear: it provides a machine that doesn't compromise for those whose main earphones are IEMs but don't want to be at a loss if they one day connect large headphones. With 361mW output, it offers a clear driving headroom over the entry-level 01, and high specs such as PCM 768kHz and DSD256 hardware decoding are all included, priced at 349 RMB.

Parameter	02 Value	What This Means
Output Power	361mW	Drives most headphones to healthy volume without issue; essentially fine up to 150Ω
PCM Decoding	32bit / 768kHz	Same specs as 02 Pro; plays master-grade files directly
DSD	Native 64/128/256 + DoP	Hardware decoding; no compromise in format support
Signal-to-Noise Ratio	130dB (4.4mm) / 125dB (3.5mm)	In quiet late-night environments, background noise is not noticeable
Distortion	-115dB (same on both outputs)	Below audible threshold; clean sound
Noise Floor	1.02μV (4.4mm) / 0.85μV (3.5mm)	Hard to hear noise with highly sensitive earphones
Impedance Adaptation	16-600Ω	Covers all standard sizes
Connectivity	3.5mm single-ended + 4.4mm balanced	Dual outputs; easy cable pairing

Differences from 02 Pro are focused on output power (361 vs 551mW) and extreme signal-to-noise ratio. Simply put, if you don't use high-impedance over-ear headphones at 300Ω level, this difference is mostly inaudible most of the time; but the price difference is 150 CNY.

For daily use, pair your phone with a 4.4mm balanced upgrade cable and in-ear monitors – this is the most comfortable setup for the 02. On weekends, if you want to drive over-ear headphones, models under 250Ω can be handled by switching to high gain. Android users should enable USB exclusive output in their player app to bypass the system mixer.

The gain modes and DAC filters follow the same logic as the 02 Pro: use low gain for IEMs and high gain for over-ears; adjust the fast/slow roll-off filter according to your preference – no need to overthink it.

• Suitable for: those who primarily use IEMs and want to leave room for full-size headphones; those who are torn between the 01 and 02 Pro, with a budget around three hundred and something.
• Not suitable for: those who are determined to drive 300Ω+ high-impedance headphones—go directly with the 02 Pro, as the difference in power will become increasingly noticeable.

Another note: the 4.4mm balanced upgrade cable can fully unleash the 02's balanced output advantage, and spending a few dozen yuan more than the single-ended cable is worth it.