PX25 SET amps-Art Audio, Audion, Wavelength???

Fellow Audiohpiles,
I am considering a SET amp and in particular a PX25 based amp but to date have only located 3 brands:
* Art Audio PX25 (US$6,500)
* Audion Silver Night MKII PX25 (US$5,495)
* Wavelength Saturn PX25 (price?)

Are there others you recommend I investigate?

Of the three listed above how do they compare - is one head and shoulders above the others? I know this is subjective but any insights would be appreciated.

thanks very much,
kevin