I never even considered using a 70v system. I thought those were just for PA, churches, etc. I am looking to play my system through out my house with CD's, radio, ipod... If I used an impedence matching unit like the niles sms-10c(http://www.nilesaudio.com/product.php?prodID=SMS-10C&recordID=High%20Power%20Impedance%20Matching%20System&categoryID=Speaker%20Selectors&catcdID=7&prdcdID=FG00260) wouldnt this do the same as a 70 volt system. Also i could use impedance matching volume controls set at 8x with 12 speakers and get an impedance of 5.3. I really dont care for a speaker selector unless i had to. So now I am completely lost.. I could always sell the adcom if it was necessary. They are going on ebay for about $400.