Any recommendations for aftermarket C-7 power cord for Bluesound Node 2i

Ice Age Audio or Cullen Cables,
Both are really good!

After extended listening, the carbon fiber coax sounds like it has wider frequency response and dynamics than the optical cable. Since my DAC allows instant switching from one input to the other it's easy to do an instant A/B comparison. Seems strange that a digital cable could have that effect, but that's what I hear.

Ive had good luck with the Nordost Purple Flare C-7 power cord, and its not too over the top in price.

Best to get a Voodoo c7 adapter so you can try any flavour or power cord to your hearts’ desires. I had to get a cable support, then migrated to Furutech ncf cable booster to eventually support a thick powercord that cost more much than my vault.Does a nice $50 vs $1000 cable make a difference on the vault? Yes..but only your wallet and ears can decide better. 

+1 @buschmann. I was told years ago that digital cables make a difference and I've experienced it myself.