So is it safe to assume that a high end, cost-is-not-an-issue, multi-thousand bucks piece of equipment like the Denon 5805 would have better power cord compared to my lowly $200 Yammie HTR-5640? Or even the Denon's cord can be improved with an after-market one?

My cord is fine. It would be funny to pair my Yammie with a $100 cord. Besides, my ears are not very picky

Just curious.

M60 + QS8 + SVS PB10 + Yamaha HTR-5640 + Pioneer 578a