Without going through and doing the math from scratch, I can't say whether that's exactly right, but it does sound as though it's in the ballpark.
The winding geometry (how many layers deep do they wind the coil), the coil former composition, vented spiders and/or pole pieces and other such arcana figure into how well the critter will shed heat, so it's difficult to relate the temperature rise to actual in-the-room music playing conditions. But if you're side-stepping those considerations and looking at it purely as temperature vs. resistance rise, then I'd say you're on the right track.
Doesn't the ESP site have some notes on this (perhaps in the active crossover section?), or am I thinking of another site?
Grey
