kota1,
I tried the XD with two different amps. Both amps have slightly different gain. I don't notice any difference. Both amps are fine with the XD. I believe a few db difference between amps is hard to notice, especially in the bass. Basically no issue. I posted this just want to know what other XD owners are dealing with the potential gain matching issue. I personally don't think it is an issue. In fact, the XD is very good sounding speakers. Their bass is superb.