Tube Pre and SS Power? Or the reverse?

I’m highly surprised that you’re claiming that 50% of the people suggest a solid state preamp/linestage and a tube power amp.

That generally makes no sense, as the main reason for mixing and matching tubes and ss is to get a tubey sound, which the line stage/preamp has more effect on, and still great bass control by the power amp because of ss power amps higher damping factor and thus better grip on the bass.

You also generally have complexity with tube power amps due to them needing either manual or some kind of automated bias for the driver and output tubes.

The only combination of tube&tube, tube&ss, ss&ss, and ss&tube that doesn't make sense is a ss preamp and a tube power amp. 

I’ve owned many different combinations of preamp/amps and so much depends on the speaker you’re driving.  For my KEF Reference 3’s, the best combo is a tube preamp and a SS amp with ample power.  Currently running LTA MicroZOTL pre, LTA Aero DAC and a Moon 860A V2 amp.  Combo seems to work well for me.  

@mojo771 bimmerlover said it better than I could.  With your room size, SS amplification is likely the way to go.  If you want to add some of the tube magic but also blend into the fold the strengths of SS amplification, the Tube on the front end and SS on the back end can deliver.  I'm not even sure what the reverse gets you and I've never heard of anyone recommending a SS Pre and Tube Amp combo.  I've had all tube, pre & amp in my set up, all SS and a Tube Pre, SS amplification set up.  With the right SS amps, SS always delivered more control, grip and ease. A Tube pre or even the right tube DAC offered a splash of tubbiness without some of the draw backs.  Now, that's with my ears, in my set up, your ears will tell the story, entirely possible to your ears, you'd prefer a SS Pre and Tube Amplification but would think if that's the way you went, you'd want to roll with all tubes at that point.  Good Luck. 

If it must be a mix, tube pre, always. 

I'm a huge fan of the mix, by the way, and find that almost every speaker benefits from the ahem, enhancements (colorations) of the tube pre and a stiff  SS amplifier. 

Of course, quality matters a great deal, but this rule has never let me down.

For your large room, I'd recommend going for the tube pre and an MC462 amp.

I have in my large room with a C2700 with an MC462 and it is a GREAT combination. I am using Volti Rivals with a pair of REL Carbon Special subs. I like the C2700 pre slightly more than the new C2800 for tone as I had one for a short while.

My second system in my office is an MA352, paired to a D150 DAC and it produces amazing sound for much less money.  Sure it would fill a pretty large room, but the C2700/MC462 can do pretty much everything you ask it to.