So a question for me is,
If the speaker sensitivity is 85db @ 2.83v at a distance of 1.0 meter, I’m assuming my receiver is putting out 1 watt to bring the elacs to 85db, is that correct or is it more because they are 4 ohms?
Regardless,
Am I safe to assume the receiver needs 4 times the power to push the same speakers to 91db?
If that is true, why is my amp clipping at 91db when it shouldn’t be pushing more than 4 times the power required to sustain 85db?
2 watts for 85dB average output at 1 meter. But in reality, more like 8-16 watts - to avoid or at least minimize clipping of transient peaks (which are 6dB-12dB higher than average output, assuming just a decent recording).
And of course this is at 1 meter. And of course the crest factor (the difference between average and peaks) of a very good recording can be quite a bit more than 12dB....especially in the classical music genre.
Anyway, extend that to a more normal listening distance and your 2 watts will putting out roughly 78dB of continuous output in an average room A good assumption is that you lose approximately 4-5dB for each doubling of distance.
To get back to 85dB of continuous (aka average) output at that more normal listening distance, your amp will need to be putting out approximately 8 watts (instead of 2). Add another 6-12dB for transient peaks, and it will need to deliver 32-128 watts to handle them.
Now let's turn the sound up to 91dB. At the extended listening distance, you would need 32 watts of continuous power, and 128-512 watts for peaks. As you can see, with these speakers at that volume, your amp will be clipping pretty heavily. Additionally, you are pressing the speakers beyond their mechanical capabilities, which will result in even more distortion or damage.
Bottom line, these speakers are just not designed for seriously high volumes. That said, I personally consider 85dB to be the point at which music starts sounding loud, and the low 90s to be the point at which it starts sounding LOUD. Mid to upper 90s starts getting close to live venue sound pressures.
For context, I was at a Counting Crows concert a few months ago, about 12 rows from the stage at a semi-outdoor venue (Starlight Theater in KC), and the opening band was pushing close to 110dB of steady output, peaking well above 120dB. Thankfully, I had ear plugs. And even more thankfully, Counting Crows dialed it back a bit...low 100's, with corresponding peaks.