Juan,
Did you order just the 532 L/R’s or did you get a 532 HT setup?
Until I received my Onkyo TX-SR805 130 WPC, I used my 4 year old 110WPC Sony to power my 7.1 setup.
What a difference the 805 made in useable power and clarity over the Sony. The 805 is THX Ultra 2 certified and I highly recommend it.
Although the Yamaha 1800 may not be THX certified it appears to have a power supply that can drive a 7.1 setup all channels driven at rated power equal to the 805.
There are quite a few Onkyo, Denon, Yamaha, Pioneer and Marantz owners here who are satisfied with their purchases.
Wait till you see the Aperions in person, you wont be disappointed.
Jack