... will this be too much for the LFD’s gain?The position of the volume control you would use is not directly related to the power capability of the amp. It is related to the gain of the amp, although generally speaking (and with numerous exceptions) there tends to be a **loose** correlation between amplifier gain and amplifier power.
The Logos MkII is spec’d as having a gain of 39 db, which is reasonable for an integrated amp although perhaps a bit more than average.
A spec does not appear to be provided for the gain of the Classic One MkIII. You might email Upscale Audio or Pathos and see if they can provide that number. The only way there would be a problem, though, is if the gain of the Classic One is **much** less than 39 db (say less than 30 db or so). I doubt that is the case, but if it were it would mean that with the Logos you might have to use the volume control undesirably close to the bottom of its range.
I can’t comment, though, on how optimal a match the Logos would be for your speakers.
Good luck. Regards,
-- Al