\(8\) musicians participate in an art festival. The organizer is going to plan \(k\) concerts. There are \(4\) musicians performing for each concert. If two musicians perform together in the same concert, then it can be said they have co-performed once. It is known that any two musicians have co-performed an equal number of times. For example, if \(A\) and \(B\) co-perform \(5\) times, then \(A\) and \(C\) must co-perform \(5\) times as well, \(D\) and \(F\) also co-perform \(5\) times, etc.
Find the minimum possible value of \(k\).