Your amp should be a balanced design with XLR inputs, because Wadia sounds better with XLR than RCA. I had my 861 directly connected to the Krell FPB300 and this worked fine.
Other than the requirement for balanced operation I don't think that your amp has to fit the Wadia 860X, it should fit your speakers.
Other than the requirement for balanced operation I don't think that your amp has to fit the Wadia 860X, it should fit your speakers.