OLLO Audio S5X: how much amplifier do you need?

The OLLO Audio S5X is 50Ω with a sensitivity of 95.2 dB/mW, which is 108.2 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 3.0 mW, or 0.39 V across the drivers.

That puts it in the easy category. A phone, a laptop headphone jack or the cheapest USB dongle will drive it to painful levels. Of the 280 sources in the database, 280 have comfortable headroom. The cheapest portable source that does the job is the Apple USB-C dongle (US) at $9.

Sensitivity here is in dB per milliwatt. Manufacturers often quote dB per volt instead and leave the unit off, which is the single most common reason online calculators give answers that are 10–15 dB wrong. The converter explains the difference.

OLLO Audio states this as 106 dB at @ 1kHz RMS @ 0 dBu (i.e. SPL at a stated input VOLTAGE, not per milliwatt) — an SPL at one specific drive level expressed in dBu, the studio unit, rather than per milliwatt or per volt. 0 dBu is 0.7746 Vrms, so at 50Ω that level is a known power and the 95.2 dB/mW above is the result. It is a real published figure, just written in a unit nothing else in this database uses — and reading it as if it were dB/mW would make this headphone look 11 dB easier to drive than it is.

The maker adds a power recommendation of its own: OLLO publishes no power handling and no recommended amplifier power; the product page's only drivability statement is the impedance line "~50 ohm - smart devices ready".

Source: olloaudio.com, olloaudio.com, cdn.shopify.com. How this data was built.

Most people listen between 75 and 85 dB. The 100 dB row is the one worth planning around: it gives you headroom for dynamic peaks without designing your system for a volume that would damage your hearing in under fifteen minutes. The safe listening calculator puts numbers on that.

Every source in the database, judged at 100 dB SPL into 50Ω. “Headroom” is how much power is left over above what the headphone needs — 10 dB means ten times the required power, which is what you want for dynamic peaks.

Hiss. At 108.2 dB/V these are sensitive enough to reveal a source's own noise floor. The noisiest source in the database, the Schiit Vali 2+, would put its hiss at roughly 16 dB SPL in these headphones — clearly audible in quiet passages. The hiss calculator lets you check your own amplifier's noise figure.

Output impedance. At 50Ω these want a source output impedance below 6.25Ω to satisfy the one-eighth rule. 34 of the 280 sources here miss it, the worst being the Bottlehead Crack (OTL kit) at 120.0Ω. Above that threshold the source starts shaping the frequency response. Check yours here.

Or open the comparison tool to put any two models side by side, or browse all 578. Or see every OLLO Audio headphone in the database, and how much of what this site says about them came from OLLO Audio’s own documents.