The 1/4" inputs on the mixer are for things like keyboards and samplers, etc. There are 8 dedicated tape send and tape returns on the mixer in good old RCA jack format.
HINT;
When you plug in a 1/4" plug into the line inputs on the mixer, it cuts off the RCA tape in jack when you are using the main mixing strip so, on mixdown, unplug any 1/4" plugs that are on channels 1 - 8 on the mixer.
And, yes; you'll need 16 cables in total. 8 in. 8 out.