Maybe buy one of these for around $25. They usually come calibrated when new.
Mine says my ambient sound is about 30 dBA. My house is deep in the woods with a cul d' sac road.
My maximum listening level,
not very often, is about 96 dBA* at my favorite chair.
Voila! 96-30=66 dB dynamic range. With the HVAC running, knock off 6 dBA for a dynamic range of 60 dB.
Further, I am about 4 meters from my speakers. Using the rule of thumb of 6 dB lapse for each doubling of distance beyond one meter, I am asking them to play at 96+6+6=108 dBA measured at 1 meter from each speaker.
Further still, my speakers are rated at a sensitivity of 86 dB at 1 watt at 1 meter. Thus, my trusty Emotiva amp is having to produce about
120 watts at the peaks of music. That's 1 watt+(10x10)+some more=~120 watts, using the rule of thumb that 10 dB more requires 10 times the power.
Even further still, if I am listening at a more typical level of 80 dBA at my chair, the amp is loafing along at about 6 watts. Maybe that's why distortion at low amp output levels is just as important as at full power, eh?
*Before you get all frothy-at-the-mouth over 96 dBA, tests show that symphony orchestra conductors often hear an FFF passage at ~120 dBA. I'm yet to see my first conductor wearing hearing aids.