I haven't hooked up the 673 yet so can't give an opinion based on the sound quality. However, I have been EXTENSIVELY researching receivers for my next purchase and the 673 has received SO many positive reviews that I'm very confident in it's performance. It's a best seller on amazon with a solid 5 start ratio, Whatifhifi product of the year. The 675 looks very similar with just slightly more power and a feature that let's you watch high quality material from your cell phone, on your tv............who the heck wants to do that. I say jump on my band wagon and take your chances with the 673 for $200 less.