Worth upgrading powercord for Denon AVR 4308ci?

A power cord with better connectors will improve performance even on an electric kettle. There's no reason not to try out a better cord on your Denon, just don't spend too much money. Keep 90%+ of your savings for the unit that will replace the Denon and bring your system a level or three higher.

Power cords can make a surprising difference but they really should be considered tweaks. Spend serious money on major components and don't let tweaks eat into the kitty for those.

Have fun!

Based on my own experience of the improvements I've heard when using this power cord on mid-fi equipment, I recommend the PS Audio XStream Prelude. You can get one on sale at Audio Advisor for about $100. I've used mine on an Oppo DV-980H, Boston Acoustics AVP7 pre/pro, and an Onkyo A-9555 integrated amp, with uniformly noticeable, good results. It practically transformed the Onkyo and made it come alive with better transients, ambience, detail, and soundstage.

I also get good results with the Monarchy Audio AC-1 at $89, but I like the PS Audio just a little better.

I haven't tried this one, but another budget power cord that looks promising is the Shunyata Research Venom at $99.

Thanks for the feedback. I will let you know how it sounds!