@handymann
Yeah, trade-in won’t get you much unless you can use it as a bargaining chip for a dealer that’s willing to cut into his margin. Probably better off selling the Urushi yourself.
The stone Koetsus are all wonderful, though unfortunately I haven’t heard an Urushi. The differences between Onyx, Jade, and Coralstone are all relatively subtle. They each have better (more powerful and clean) bass response than the RSP. The Onyx is a pretty excellent all-rounder. The Coralstone is a slight bit more warm, organic, and fleshy sounding. It is probably the best sounding, overall, by a small amount. But they’re all great and give the full dose of Koetsu magic. Don’t stress too much over the stone differences. I highly recommend any of them!
Do give consideration to the amplification needs of a 0.3mV output platinum. The Bob's Devices Sky SUT's make for an extremely synergistic pairing with any stone Koetsus, for a very reasonable price.