A:Answer The SC-C22 is a 6-Ohm speaker, but SP-EC73 is a 4-Ohm speaker. If the AVR can drive a 4-Ohm speaker then you can use SP-EC73 in place of SP-C22. The SC 1223-K is rated for 4-Ohm speakers in 2-channel mode, but you will have to look in the manual (available online) to verify that 4-Ohm center is OK.