Check out also Peachtree amps up from decco2.They will work fantastic with your RX6 and imo. better than a19.Ideally you would look out for a 125se if new.Remember a very good dac is also integrated in them when you compare price.Don´t worry if you go 2.nd hand,their support service is good too.
As for the sub,if you think you really need one,the rx6 are bass heavy, I would go for the SB 2000 instead.For HT purpose the PB will reach deeper I guess because of the ports.My choice would be the SB though.Both SVS are a good choice imo. at their price.