interconnects vs speaker cables vs power cords - which make the biggest difference?

IMHO the speaker cables are the most critical.  I'll throw in a plug for the brand I use, Jena  Cable which are simply insulated braided copper. Then ICs, I have yet to hear a meaningful difference between power cords.

impossible to answer imo but you may get some good pointers along the way!

WRT to Power cables - I have observed  that the components in my system with the "lowest quality" power supplies tend to benefit more from a power cable upgrade than components having a higher quality power supply

e.g.
- my Bifrost DAC performed noticeably better with a good power cord.
- whereas my NAIM amp, although it improved, the improvements were more subtle.
- my Simaudio Moon Phono stage was somewhere between the two.

Also, If you have components with Wall-wart power supplies - find a quality replacement. with a quality power cable - It makes a huge difference

If I had to start again, I would start by upgrading the power cables first, because these allow the components to operate to their best abilities. Then followed by IC's and then speaker cables.

Regards...