I have their little brothers, the kappa 5.1's and also their big brother the kappa 8.1's
These speakers aren't the easiest to drive and also aren't the most efficient thus I would highly suggest whatever receiver you get, buy one with pre amp outputs. Then when money is available buy a 2 channel amp to power the kappas, they sound much better this way.
These speakers aren't the amp killers that the 9/9.1 was, but they still need a bit of juice to sound good.