Room & listening
Target SPL
How loud you actually listen, in decibels at your chair.
Simple
How loud you actually listen, measured in decibels at your chair. Quiet background listening is around 65 dB; a lively session is 85 dB; live-concert loud is 100 dB+.
The theory
SPL (sound pressure level) is a logarithmic measure referenced to the threshold of hearing (20 µPa). Every +10 dB is roughly a doubling of perceived loudness but a tenfold increase in acoustic power. The engine treats your target as the average level — the steady loudness you'd read on a meter — and builds the peak requirement on top of it.
For experts
85 dB isn't arbitrary: it's the reference playback level baked into film mixing (the SMPTE/Dolby calibration target, per channel) and a sane proxy for "engaged but not hearing-damaging" listening. OSHA's 8-hour exposure limit is 90 dBA, and risk roughly doubles every 3 dB above that, so a 105 dB peak is fine for transients but you wouldn't want it sustained. Because power scales as 10^(dB/10), asking for 95 dB average instead of 85 demands ten times the amplifier watts — which is exactly why "just turn it up 10 dB" quietly wrecks a headroom budget.
Sound pressure level is logarithmic, referenced to the threshold of hearing.
Every +10 dB of target level costs 10× the amplifier power.