Help!

My setup is a Sony STRDH190 paired with klipsch r-50 passive speakers and sounds loud and clean but I also purchased klipsch r-620f tower speakers, they are also passive speakers. I hooked them up and it sounds a quieter than the bookshelf speakers And I only listen to vinyl on these 4 speakers. Is there anything I can do to fix why they are quiet???? I checked my settings and it says it's doing 8 ohms should that be 16 ohms and how can I change that?