Rotel 1075 5-Channel + Rotel 1068 pre/processor

I recently purchased the Rotel 1075/1068 combo for HT. I wanted a system that was good for HT but also for two channel stereo listening. My former equipment consisted of a Classe Seventy amp and Classe Four preamp (a bit dated I know!). Anyways, the sound of the Rotel combo is fairly good (still breaking them in though), but I'm finding the bass response a bit lacking from what I was accustomed to. So here are my questions: 1. The Rotel combo comes with very cheap two prong power cords that go to my wall outlet. Will upgrading to a semi-decent power cord help my sound quality audibly? If so, what power cords can someone recommend for my amp/processor combo? 2. Any recommendations on interconnects between the two units? 3. Any recommendations on speaker cable as well? Any advice anyone could give me to help improve the bass response would be greatly appreciated! My system consists of:
B&W Concept 90 CM2 speakers for fronts
B&W DM 600 S3 for surround speakers
Rotel 1075/1068 as mentioned above
REL Q150E sub (primarily used for HT)
B&W HTM Matrix design

Thanks for your help!