Ooooops...
Sorry for the late reply - and unfortunately, I have no info for you. :thumbsdn: Beleive it or not, Advent seems to be very shy about their impedance ratings - I have a set of Baby IIs, a set of Prodigy Towers, and TWO sets of Legacys... but nowhere on any of them is there an impedance rating. I even have the original paperwork for my Legacys - but, you guessed it - NO impedance spec!
I'll keep my eye out, and if I see any Advent promo literature with impedance specs, you'll be the first to know. My curiosity has been piqued.
PS>> For what it's worth, I've run two sets of Legacies simultaneously with several receivers over the years, and have never had any problems...