Great 2 channel or 4/5 channels?

I have a concerning issue. I have a pair of amazing Casta model C's. An Audiozen 2 channel amplifier. On trial with me is an Audiozen Tube pre amp and tube dac. I also have a Core Audio Technology server with Flac files(USB stick). Music is simply stunning. Soundstage is large, dynamics are great, information through this set-up is world class to me.

On 2 channel with movies it is just as good. I presently use an Oppo 103 that needs to go as I find oppo to have very thin midrange and bass range-trade-off to the high resolution(103/105)they have. Just awefull. I was thinking of a higherend used pioneer or marantz with anything but an Ess saber chip.

I do have a matching pair of Casta D6 surrounds that are not hooked up as I do not have another 2 channel amplifier and a processor for channel processing and steering.

My main points are: I definitely don't need a centre. I could use a sub for lower octaves than my Casta C's 15" woofer in each speaker just for movies. Music is palpable, chest tight, punchy and dynamic. My concern is utilizing my rears for that surround fill-in but would mean downgrading to pre processor for the 3rd and fourth channels. Once I pull the dac and pre and add a processor, I lose that 20-30% of information.
Or should I stay with 2 channel for movies?
It seems to be a trade-off with a processor as it sucks all the positive points from the 2 channel set-up. To me surround/side information is critical in movie watching, and my surrounds have crazy information from the dipole setup. I am trying to get the best of both worlds here but it is really not possible unless one has two seperate set-ups in two different rooms.

If anybody has any suggestions on what I could do or use as a processor and universal bluray player for both worlds it would be appreciated. I don't yet have a budget but it isn't an issue.....thx in advance.
Aside from Mac, AudioResearch, BelCanto and C-J had good MCH analog preamps. I currently use the AR.
I have though of trying the Emotiva XMC-1 as I had previously in the past had a UMC-200 which was pretty good. The XMC-1 has Dirac which is one of the best. I did want to stay with the separate dac/pre senerio as it has no processing. Even with a multichannel analogue processor there is still processing being done once or sometimes twice which to me means degradation. I may try this server and see if the Dirac program can be put on it. But I will only run 4.1 or 4.2 channels for home theatre. A centre is not needed. I will research the other processors mentioned. Thx.
The version of Dirac on the XMC-1 is limited in a number of ways. The PC/Mac versions are more expensive but more capable.

Again, the items I mentioned are preamps, not processors.
I would like to find a Audio Research Mp1. I think that fits what I am looking for. If anyone know where I could get one just EM me. Thx.