2 Acoustic Zen Silver Reference II IC's too much?

here's a novel idea
swap out one of your silvers to a single channel both the source and pre to power and hear the additive affects (don't know if you have a balance knob on your preamp, or you can just hook up the one channel)

I've used Matrix reference and paired it with StraightWire Crescendo which is a very revealing and tonally balanced interconnect (which worked great between pre and power amp)

I'd try the AZ SRII first to see if it's too bright. One downside of the Matrix Ref. IIs is they can slow things down a bit relatively speaking, which may or may not bother you but something to take into account besides tonal differences.

I currently have one pair of Silver Reference II and two pairs of XLO Signature 2 all balanced cables. The XLO is a more dynamic cable and has more energy in the higher registers(some can associate that as brightness) than the Acoustic Zen Silver Reference II, and I am using both XLO cables throughout my main system. The "softer" sounding XLO now connects the subwoofer to the preamp.

The point to be conveyed here is I find the Silver Reference II to be a softer sounding cable in comparison to the XLO. Sonus Faber Grand Piano speakers especially the Concerto version are warm and slightly rolled-off in the treble and I'm little surprised you are getting a silvery(bright) cymbal sound as opposed to a bronze(warm) sound. If that's the case I suppose Audphile's advice may be a safer bet.