Let me see if I am interpreting you correctly: You have chosen to put the pre/pro up front, you will have short interconnect runs to L/C/R amp(s) up front, short speaker cable for L/C/R up front, approximately 40-foot interconnects from pre/pro to surround/rear amp(s) in the closet with up to 30-foot speaker cable to surrounds/rears?

You are also placing your source gear near the pre/pro?

If all the above is true, and you are using interconnects made from well-shielded cable such as that manufactured by Belden or Canare, and the speaker cable is of sufficiently low resistance, and the cable runs, either interconnect or speaker cable, are not involved with strong interference fields, like those that would result from running audio cable in parallel with power wiring, you should be OK.

It would be best to run a test installation prior to the formal install just to determine if you will have any trouble that will present problems. One that may sneak up on you might be a different ground potential or ground loops between the two locations in your room.

I hope that has been helpful.