HiBy R6 Pro II: power output and what it will drive

The HiBy R6 Pro II is a portable player at $750. It delivers 750 mW into 32Ω and 140 mW into 300Ω, which ranks it 91 of 280 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 557 of the 567 dynamic and planar headphones catalogued here, enough but not generous on 8, only marginal on 1 and not enough power for 1. HiBy publishes its audio specifications as images rather than text, and their wiki lists chips and interfaces but no power rating. Nothing here could be traced to a readable HiBy document.

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 4 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 33 dB SPL, which you will hear between tracks and in quiet passages.

At 0.6Ω output impedance, the one-eighth rule says this source suits headphones of 4.8Ω and above. 1 of the 567 models here falls below that. The one model below that line is the Symphonium Titan, 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.

Of the 280 sources here, 69 do everything the HiBy R6 Pro II does as a headphone output: reach 100 dB on every headphone it reaches. The cheapest of them is the FiiO KA11 at $29, against this one’s $750 — $721 less, and a USB dongle rather than a portable player.

The cheaper one also publishes an output impedance and a noise figure, which the HiBy R6 Pro II does not — so on the paperwork it is ahead, not merely level.

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 Astell&Kern SR35 · vs Cayin N3 Ultra · vs HiBy R8 II · vs HiBy RS6 · vs Shanling M3 Ultra · vs Sony NW-ZX707. 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. Or see every HiBy source in the database, and how much of what this site says about them came from HiBy’s own documents.