Cleeds, note that he said more than one "active" XLR output. I interpret that to mean he was referring to the two output connectors on each channel each being driven by its own dedicated output stage, which appears to be the case for the Classe CP-800. But based on schematics I’ve seen at arcdb.ws most or all ARC line stages and preamps which provide two XLR outputs drive both of them from the same output stage, and simply jumper the two connectors together internally. I believe that the same holds true for the great majority of preamps and line stages from other manufacturers which provide two pairs of XLR outputs, and for RCA outputs as well.
In those cases the preamp’s output stage will have to drive the input impedances of both of the power amp inputs to which it is connected, just as if a splitter were used.
And the results could actually be worse than using a splitter, because if a short splitter is placed near the two amp inputs the cable capacitance seen by the preamp’s output stage would essentially be just the capacitance of one cable rather than two. The splitter approach being most likely to provide better results if the preamp’s output impedance is high at high frequencies, and if cable length is long (cable capacitance is proportional to length), and if the cables do not have low capacitance per unit length. In that situation some degree of rolloff and/or undesirable phase shifts may occur in the upper treble region if two long cables are used, which could be avoided or minimized if a short splitter is used in combination with a single long cable.
Regards,
-- Al
