Bi-amping Pass X.5 matches X.8 / XA.8 / X.5 / XA.5

Dear all,

please advice me!

I own Passlabs X.5 monoblock and like it very much.

Now, I want to try bi-amping.

Is it a good idea to buy another X.5, XA.5, X.8 or XA.8?

Please explain your opinion or share your experience deeply.

Thank you so much!