Already out on PS4
When Harmonix first announced Amplitude, it was gunning for a PS3 and PS4 release. But January came, and nothing was said about the former. According to the publisher the wait is over, and it will hit last generation systems sometime in April after certification. Harmonix notes that backer codes will have Cross-Buy capabilities.
I found this round of Amplitude to be less compelling than the first, mostly because it lacked a distinct identity this time around.
PS3 version, physical rewards, artbook info [Kickstarter]