Best interconnect for Spectral amp, RCA or XLR??

Hi guys,

What is the best way of connecting Spectral pre and power together? RCA or XLR? Has anyone ever tried A-B test between these 2 choices of connection? Many people told me Spectral sounds their best with RCA interconnect (must it be MIT cables?). Is this true?

I've just bought a used DMC20 series ii together with a pair of DMA360s last 2 weeks and connected them with Transparent Ultra XLR interconnect. My speaker is Avalon Eidolon and the speaker cable is Transparent Reference. Any recommendation?

Thanks

Benn