Hi, I am using the SDA 2.3TL speakers currently. I just bought a used Sunfire signature amplifier (early version it seems, fixed powercord & plastic binding posts, signature on the front), but I am afraid it is not a "common ground" amp. How do I even know its common ground? I do not have the A1 interconnect cable, just the normal straight cable. Anyone has owned this amp & used it successfully with the SDA? I don't wish to blow up everything on connection. Thanks!