The Chardonnay will work well with the Pass X250.5 - my Syrah was great with my X 250.
It (Syrah)has ample gain for my Audiopax 88s but way too much for my friends Mcintosh monoblocks, very noisy but I think the problem lies with the power amps not the Supratek.
My older (7 year old) Supratek has possibly just less than half the gain of the Syrah, the phonostage has sod all gain.
It can be something of a lottery with these without a spec sheet to go by.
I imagine things will be settling now Mick has a workforce but older ones can be a tad 'unique', leading to hiccups.