I guess I'd make the assumption that the reference was 1 watt input, rather than gaming the sub-8 ohm impedence vs. 2.83V thing, but you never know.

I read somewhere that 109dB SPL is one equivalent to 1 (acoustic) watt.

If the claim above were true, that would seem indicate a conversion efficiency of over 97%. That seems like a much higher efficiency than I would have thought was possible.

Am I looking at this correctly?