Best matching amp for Wilson W/P6, any sudgestions

There are too many unknowns for me to answer your question in any way that is likely to be useful to you. Listening room size, acoustics, types of music and maximum listening volume are all critical to presenting any informed suggestions.

You have many good options.
I used a BAT VK500 with BatPak & a Pass Labs X1 with my rig:
(Marantz DV8400 Universal - Nottingham Mentor TT with VDH Colibri Cartidge - Pass Labs XOno Phono Amp - Tandberg 10X-02 Open Reel Deck & TCD 440A Cassette Deck) & never looked back.
All the power & punch that you could want (Unless you are a tube freak & expect a more/sweeter midrange/with less bottom end).
MY SUGGESTION:
If you want more power - try the BAT VK 600 with BatPak AWESOME!
I sold both the VK500 & X1 as I am now into 7.1 HT, but will not/never part with the Watt puppies & the rest of my system.
I also have another 7.1 HT system & 3 turntables (Phase Linear 8000 with Ortofon MC 30 Cartridge & MCA 76 Head Amp - Audio Meca Romance/with Romero Arm & Dynavestor XX 20H Cartridge - Wilson Benesch ACT TT with 2.0 Arm & VDH Frog.
I still smile everytime I listen to the Wilson's (probably the best investment I have ever made).
Regards
Richard

I understand that Wilson has been demo'ing with Spectral and ARC of late.

ARC uses big Wilsons, among others, to voice its equipment.

One of my dealers told me that the CAT amps have special synergy with Wilson Grand Slamms, but which iteration of the Slamms I cannot recall, and the WP 7 is pretty different from the Grand Slamms.

I agree with Siliab and just checked your system. I'd say you could use some tubes. In this regard, the CAT amps tend to work well with your Transparent cabling.

anything in piano laquered black.

The Watts/Puppies are rushlessly revealing of the electronics you use. That's their strength and weakness. You have two different way to go.

I have used a pair of BAT-VK60 successfully. The midrange and imaging are simply stunning. The bass was very dynamic but not the tighest possible. The high is extremely smooth; there some information missing at the very top. The soundstage is large but not completely wide open (tube amps usually don't go high enough to provide the best soundstage).

Your best choices of solid-state amps are the ones with high current and very wide frequency response like the Spectral to take full advantage of the Watts/Puppies capabilities. The advantages are numerous: great bass, very detailed highs, and huge soundstage. Watch out, however, for a little hardness in the sound--just a smidgeon, mind you, but it's there and it is hard to remove completely. You can try different speaker cables for fine tuning.

I overcorrected with the Rowland Model 7 monoblocks: the hardness was completely gone but the sound was a little too polite for my taste. I get outstanding results with my new switching amp: very dynamic sound with great bass, smooth midrange, detailed high, and huge soundstage. There is a little hardness in the sound but most of it is eliminated with the right speaker cables (OCOS transmission lines, triple run; double Straightwire Maestro) and a good power conditioner.

The bottom line is the Watts/Puppies will reveal everything in your system, warts and all so you have to be meticulous about everything upstream, especially in the high frequencies. With bad ss amps, these babies will drill holes in your ears.

Happy listening.

PS: I could not find any electronics in black lacquered piano finish as Jay Douglas suggested. Sorry.