I have RtiA7s front CC CSiA6 FXiA4 surround running them with Yamaha a2000. I like the sound, however, my friend came over last night and suggested me to add Emotiva XPA-3 or 5 to my system. My question is, is it really add more to what I have now. Will the sound quality improve significantly? Is it worth to spend $600/$800? Thanks for your comment.