Tube then Class D

NO! Tubes are not "warm" sounding devices! They get hot and glow. This has visual appeal but nothing to do with sonic quality. A tube circuit amplifies an electric signal with more or less distortion. Transistors do the same - only with less noise/distortion. Either tube or transistor circuits can be engineered to have identical harmonic distortion/noise. But the transistor circuit will not degrade over time, unlike the tube circuit. My advice is if you really want a warmer sound change your speakers - not the electronics!

Don't listen to the about-to-chime-in tube fanatics! I have a large collection of tube gear but I am realistic enough to recognize its limitations.

That Willeston tube amp has an output impedance of several ohms. It will interact with any speaker's impedance curve and act as a tone control. Do you really want to subject your music to a tone control you can't turn off?

Joe, lots of people soften their Class D with tube preamps, so that is doable, but I don't see how you can use an amp as a phono preamp. Initially I thought you were going to use the preamp section of the Willeston into the class d, but it looks like there is no pre-out only a pre-in, so that won't work.

The cheapest tube preamp I would recommend is the Quicksilver. 

Okay a tube pre-amp could be used.   But a tube amp cannot be used.   I was under the impression that tube amp and in this case a tube preamp has a different sound.  Sometimes described as warm, with better holographics, better soundstage, warmer sound in the mid range.  I just thought maybe the tube characteristics would be eaten by the digital.   So why waste a grand or more if the sound quality is not more pleasing.  I might as well  just keep the $200  mani2  and spend a grand on vinyl.

You MUST have a phono pre-amp. It can be separate or built in but you need one that translates the input signal into the corrected RIAA curves.