In 2009, The Radio City Rockets got an upgrade of their wireless mic system. Each dancer had a microphone installed on each tap shoe. Most dancers wear 2 shoes at a time, and they usually have costume changes in each performance. It adds up to around 300 microphones, using an 80 channel wireless receiver system. That's a whole lot of technical complication.
Judging by this photo, the upgrade to their look this year seems far less complicated.