As stated, use RCA cables from the 7.1 output of the BDP to the AVR's 7.1 input. Since your AVR does not have HDMI, this is the only way that you will be able to get lossless (DTS-MA and DD-TruHD) audio. 
The link to the RCA cables in eljay's post is a good recommendation; you will need 4 pair (8 total for L, R, C, LS, RS, LR, RR, and LFE) for a 7.1 connection.
The link to the RCA cables in eljay's post is a good recommendation; you will need 4 pair (8 total for L, R, C, LS, RS, LR, RR, and LFE) for a 7.1 connection.
