i linked-up my M90 and and GF-999 together today by a audio cable(L&R type),but i found that nomatter which bbx would sounds worse when they recieves signal from another's line-out does the line-out of the bbx not really built well or there are any other kind of problems?? thanks~!!
I have found that the best way to do this type of comparison is to play from a separate device and run a splitter for the RCA cables. This way you can run a cable to each box's line-in and they both are using the same audio source.