Subwoofer long runs multiple connections.

Wife now wants sub EP 500 set up in back Left corner of room behind my King recliner char. I have a cable outlet there. Want to use that connection RG59 with multiple splices over the wall down the hall ending at the amp. Confirmed no short after connecting 3 runs of coax. Distance for total Coax is estimated at 100 ft.

Question? Will there be any sound quality issues with this long coax run.

Glen, even for the highest audio frequencies RG59(or even smaller coax)would be good for over a hundred feet. The cable to a sub has probably the easiest job in all of audio since it is just responsible for analog signals from about 20-100Hz. The usual precaution to not run it near power lines for a significant distance should be taken, but the ordinary well-shielded coax will rarely run into a problem with interference.