Never seen the inside of the Rotel amp so it is hard to say for sure. I did a similar project on a Sony 707ES integrated amp a few years ago. It was not a difficult task to remove the 18 gauge cord and solder in a 14 gauge. The new cord was not a perfect fit through the hole but it worked fine. Just be sure polarity is correct.
Now the big question. Did it improve the sound? Can't say I noticed any difference.
Now the big question. Did it improve the sound? Can't say I noticed any difference.