I bought a Perform VK a month or so ago. I tried it out and it works great. BUT I already had a T.C. Helicon Harmony M, made in 2008, and it is simpler for my needs.
The VK has audio inputs and a mic that samples your music, such as guitar, keyboard or MP3, and when you sing it selects the correct Harmonies, depending on what you have set. It also has midi input that does the same thing. And it quickly attaches to a mic stand if you want.
The Harmony M ONLY has midi input, but that's all I need or want it to do. And, I'm used to using it.
I paid $249 and will take $190. shipped to U.S. It will pass for new as I only used it a couple of weekends. For $20 more dollars I will include a 3-button footswitch. It's a Digitech but works perfectly with it.
https://www.sweetwater.com/store/detail/...vocal-processor