Zavato, you can find plenty to read about on why the shortest length possible of speaker cable is the best option. A longer signal connecting cable is a better choice than a longer speaker cable. As dweller mentioned, if your speakers are capable of bi-wire connectivity, and if you are able to centrally locate your amp between your speakers (and thus using a longer signal connecting cable), then with 16' you have sufficient length to make a double bi-wire configuration of 2, 8' pairs. That would be the best option for utilizing and repurposing what you presently have and creating a superior solution of connectivity. I recommend having Analysis Plus do the re-terminations so you know it was properly done by those who know their products best. The result should put a smile on your face every time you listen to your system.
Enjoy the music.