Sneaky bastards. If only we had a set of rigid standards designed to give usable information for us consumers...Pretty much, yes, you can mostly assume that. But beware. Manufacturers will pick the highest output voltage they can, even if it is at extreme level of distortion in some cases. Pro amps will often reference the BTL (bridged) output power as it has twice the voltage. And, at the other end, they will specify an A-WTD curve or a curve that kills off the mains related contributions (50/60Hz and harmonics) like a 400Hz HPF (aka hum and noise filter).
You have really helped my understanding of a few things today, so thank you for that. Keep your critical voice and strong opinions!
