Is this a good idea?

The splicers or couplings will not hurt anything. Just make sure to keep all the cables running the same/correct direction. Haven’t had a pair of Cardas in years so don’t recall if they’re directional or not but they are as the shield is only tied to one end. If there’s no direction arrows on the jacket then keep all the lettering going the same direction. Cards are litz construction so the wire itself is not as noticeable direction wise as solid core wire, but it does matter if the cable is shielded and that is usually only tied at one end which will likely change how it sounds so you need to experiment once your cables settle in. You probably already knew all this but just Incase I thought I should post.

Enjoy your new cables.

Well they carry the same amplitude signal from the CD player regardless of volume, so that part doesn't matter. Burning them in like this is fine. Some will say there are burn-in tracks you could be playing that will do a slightly better job, but 99% happens regardless so whatever.

My comment would be, why? If these are any good they will sound good right out of the box. Not as good, not saying that. The best stuff tends to continue improving for quite some time. But the best stuff also sounds really, really good right out of the box. No good cable needs 100 hours to sound good. Let alone a couple hundred. There's even a recent thread by some poor guy who wasted hundreds of hours hoping in vain to hear his crap cable somehow break in and sound good. Never gonna happen. If they don't sound good you send them back. Takes a day or two at most. What am I missing here?