Sennheiser HD 600: how much amplifier do you need?

The Sennheiser HD 600 is 300Ω with a sensitivity of 91.8 dB/mW, which is 97.0 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 6.6 mW, or 1.41 V across the drivers.

That is a demanding load — not impossible from a portable source, but you want a good one. 109 of the 280 sources have at least 10 dB of headroom, 116 more have enough, 36 are marginal and 19 fall short. The cheapest portable source that does the job is the FiiO KA11 at $29.

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.

Sennheiser publishes this as 97 dB/V (1 V) — a figure per volt, not per milliwatt. At 300Ω the two differ by 5.2 dB, so the 91.8 dB/mW above is that published number converted, not a different measurement.

This is the conversion that online calculators skip. Quote the per-volt number as if it were per-milliwatt and this headphone looks 5 dB easier to drive than it is — which is roughly the difference between a dongle being enough and not being enough.

Source: us.sennheiser-hearing.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 300Ω. “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 97.0 dB/V these are sensitive enough to reveal a source's own noise floor. The noisiest source in the database, the Schiit Mjolnir 3, would put its hiss at roughly 5 dB SPL in these headphones — faintly audible in a silent room. The hiss calculator lets you check your own amplifier's noise figure.

Output impedance. At 300Ω these want a source output impedance below 37.50Ω to satisfy the one-eighth rule. Of the 192 sources that publish one, 15 miss it, the worst being the Bottlehead Crack (OTL kit) at 120.0Ω; the other 88 publish no output impedance at all, so they cannot be checked either way. Above that threshold the source starts shaping the frequency response. Check yours here.

Volume is not the test. Plenty of weak sources will play these loud enough. What runs out first is control on bass peaks, where the current demand spikes well above the average figures in the table. If it sounds loud but soft, that is what you are hearing.

Worked out in advance against its own stable: vs 109 Pro · vs 99 Classics · vs AB-1266 Phi TC · vs AEON 2 Closed · vs Ananda Nano · vs Arya Organic · vs Arya Stealth · vs ATH-M40X · vs ATH-M50X · vs ATH-R70X · vs Atrium · vs Clear MG · vs DT 1990 Pro (250Ω) · vs DT 770 Pro (250Ω) · vs DT 770 Pro (80Ω) · vs DT 880 Edition (600Ω) · vs DT 900 Pro X · vs DT 990 Pro (250Ω) · vs Edition XS · vs Edition XV · vs Empyrean · vs Expanse · vs HD 280 Pro · vs HD 400 PRO · vs HD 480 PRO · vs HD 490 Pro · vs HD 505 · vs HD 550 · vs HD 560S · vs HD 569 · vs HD 579 · vs HD 58X Jubilee (Drop) · vs HD 599 · vs HD 620S · vs HD 650 · vs HD 660S · vs HD 660S2 · vs HD 6XX (Drop) · vs HD 700 · vs HD 800 · vs HD 800S · vs HD 820 · vs HE400se · vs K371 · vs K612 Pro · vs K702 · vs LCD-2 Classic · vs LCD-5 · vs LCD-X 2021 · vs MDR-7506 · vs MDR-MV1 · vs MM-500 · vs SHP9500 · vs SHP9600 · vs SR80x · vs Stealth · vs Sundara · vs Susvara · vs T50RP MK3 · vs Utopia · vs Verite Closed. Each of those pages counts the sources that drive one and not the other.

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