First World Problem in need of Solution

My problem is that I would like to upgrade my system to a 5.1 system however I am worried about matching sound to what I currently have. 

AMPs Luxman M-900u run as mono blocks
PreAmp Luxman C-900u
Subs - SVS SB4000 - these are run via XLR from PreAmp to Sub so listening is speaker A+B
DAC PS Audio Directstream 
Fronts Focal Sopra N 3 
Rears Focal Sopra N 1 
Center Focal Sopra center

Possible Solutions 
Buy a HT Processor and run rear and center out of it and use the HT Passthru on the Luxman Preamp. 
Sound is going to sound different from the rears and center than the front left and right
Thoughts: This seems like the best solution because my 2 channel listening will not be compromised

Buy a HT Processor and run rears and sub out of it. Convert the mono blocks into a normal 2 channel amp and run the center speaker into a dedicated amp. Or I could run front and rears off of the mono blocks and the center off of the the HT Processor 
Concern Potentially losing the subs in 2 channel listening. Center sounding off. The N. 3 only have one amp drive them
Thoughts: This just seems like a nightmare

Sell all my gear and replace with another brand that also has HT lineup so I could accomplish all of my goals
Concern: 2 Channel Listening is going to be compromised
Thoughts: Maybe the best option? 

Scrap the 5.2 and go to a 3.1 setup. Run an optical out from the TV to the DAC. Run the monoblocks as regular amps. 
Concern: 2 Channel listening compromised, NO BASS! Unless I could run them out of the DAC? Maybe

Can some of you who have more experience weigh in on which way you would go or which option seems "best to you".

Also any suggestions for HT processor would be helpful. 

Thanks  in advance 

I don't believe you can just purchase a HT processor. You need a multi-channel amp to run your center and rear channels and a HT Processor to run through your preamp's HT bypass. I have a 5.1 system that you can view under virtual systems.
If 2-channel audio is your main priority, then your Option #1 is most likely the best solution.  There isn't going to be any HT Processor that is going to sound quite like your Luxman C-900u preamp.  You could go with your other options, but like you said, 2-channel audio is going to be severely compromised, especially if you are using the subs to "add bass octaves" to the natural bass of the Focal Sopra.  Everyone who runs a "hybrid rig" is compromising in the 5.1 HT side of things, but that's a necessary evil.
If you did replace the amps, I would be very careful about matching.  Your Luxman amp is likely a very good match, along with amps such as Pass Labs (especially the XA series), maybe Parasound JC1 with high-bias Class A setting.

For processors, I'm partial to Krell S1200U because of the Class A analog stages, but it is discontinued and does not support the new features, such as 4K video, HDR, Atmos, etc.  There are others, but for home theater movie excitement, probably the Krell Foundation is the best way to go.
Agree with comments above that option 1 is best and that you’re not going to find a perfect match for either your amps or preamp. With that, I’m just going to dumb this down a bit in an effort to simplify things. This assumes you’re not looking for absolute state-of-the-art surround performance and would be happy with very, very good 5.1 sound that doesn’t compromise your 2-channel performance in any way. Given you’re not going to perfectly match your current electronics anyway, what about buying a very good A/V receiver with a warmish sound? This way you’re at least keeping the general character of your electronics intact, and you’re getting all the amplification and surround processing you need in one relatively cost-effective box that can be easily and economically upgraded as technology inevitably progresses. Here’s an example of an AVR that might fit the bill nicely...

While this will not be a perfect solution to your situation, it’s hard to believe this setup wouldn’t produce a highly satisfying and involving 5.1 experience. And there’s no guarantee you’ll get a much better match by going through the time, effort, and considerable expense of finding a suitable separate prepro and multichannel amp. Obviously if you’re after SOTA multichannel performance it’s worth going down that rabbit hole, but if not I think you could be very happy and maybe even pleasantly surprised with the performance of this setup (along with the several extra thousands of dollars you’ll have in your bank account). Just another option to consider FWIW. Best of luck in your quest.

Thanks guys. 

That was my feeling the best option was however finding the "right" match without going through 12 AV All in one is now the key. 

I love my Luxman gear and do not want to part with it however I do not have the room to have multiple systems. 

Marantz is where I originally started my journey in HiFi.

Is there a minimum wattage I should be looking for for the 3 Channel? 

Thanks again for your input everyone. 
You probably want at least a couple hundred watts per channel.  The best solution would be to find more Luxman amps, but they are definitely very expensive!!  I don't know if you can find a smaller M-700u that you could run mono for the center channel.  Then another M-700u for the surrounds.  Be careful when buying these from Japan because the "Japan" models are usually wired for 100V A/C (which will not work properly in the US 120V standard).

Or you can try to put in a Pass Labs or Parasound amp.  Pass Labs does not make 3 channel amps, but Parasound has an A31.  Or use a Parasound JC1 for center and an A21 for surrounds.  The JC1 can be switched to high-bias Class A which may sound closer to the Luxman signature.  Or you could try a McIntosh 3-channel like the MC303, but the McIntosh will likely be a smoother sound than the Luxman/Pass/Parasound signatures. 
I would also vote for option #1 running your 2-channel setup in bypass mode. While watching films and TV, you'll be less sensitive to differences in the sound between your mains and other speakers anyway, and this won't compromise your 2-channel playback.

Ignoring the sound character for a second, you should pick an amplifier's power output for the other three channels based on how hard the speakers are to drive and what volume you want to achieve. I'm using a Bryston 21B3 as a 3-channel amplifier, as it is one of the few 3-channel units that is capable of high power output and drive.
My advice is build your home theatre in another room and get a couple of Jbl m2 and half a dozen subwoofers and some Jbl 1400 as sides and rears 
Sorry, nekoaudio, but I disagree here.  A large power supply in the amp is very important, yes, but the sonic signature and how it reacts to signal/load is another important factor.  I have worked with several different amps (Bryston is one of them) and when you combine a very fast/clean amp like Bryston with a very warm/full amp such as Luxman/Parasound, what happens is an imbalance in sound and impact.  In that case, while the Bryston is a very high resolution amp, it will just not keep up with the Luxman/Parasound in volume/body/impact.  I have tested and experienced this personally.  The Bryston does have it place, but also in this case, I think it would be a very bad pairing with Focal speakers.  The Bryston would excel with a very warm preamp (such as Marantz) and paired with warmer type speakers (NOT Focal).  In my situation, the Bryston could not even keep up with my Emotiva XPR-1 amps, and I was testing the big 7b3 600 watt monoblocks.  I probably could have gotten the Bryston to work, but I did not want to re-work all my cabling back to gold-plated connectors and such.  The Brystons were powering left/right and the Emotiva was powering the center -- and the difference was very obvious.

The Focals are very fast and clean speakers.  If you pair them with a high resolution amp such as Classe, the sound is not bad, but it is very apparent that the bass/midbass are somewhat thin and hollow sounding.  This pushes the emphasis to the high frequencies, which makes the speaker sound somewhat bright (bordering on harsh).  Pairing Focal with Bryston would create a very thin/bright sound with no body and impact.  The Focal definitely needs a very warm full amp because the speaker is such a fast responding speaker.
How do you like the Focal Sopra center? I have the No. 1’s in my dual audio/HT set-up. Thanks. 
So the rabbit hole continues to grow:

Based on others opinions I was looking at the Parasound equipment and they have a 3 channel amp as well as a 7.1 preamp. However it does not have ARC or HDMI. Here is a link to the back of the unit.

So it looks like I would still need an additional preamp to marry to the two Parasound pieces. 

I think the Marantz may be the best bet however I have not been super stoked with their products in the past. Maybe the Rotel RAP 1580?

2) I love the Focal speakers, they hit my ear very well, they look great and fit my room well. The only speaker I have liked more is the CLX Art but they wouldn't work in my space. 

The Parasound P7 is not really a true HT Processor.  It's a 7 channel analog preamp.

For HT Processor, I would recommend getting the highest resolution processor possible, depending on your budget.  If 4K is a requirement, maybe Krell Foundation 4K UHD.  If you don't need 4K, then maybe Krell S1200U or Classe SSP-800. 

The Rotel RAP-1580 is like a HT AVR Receiver and it's probably a very good product.  But it is higher resolution and faster.  It may not be the best match for your Focal speakers, and would definitely sound different than the Luxman amps for left/right.  The Parasound A31 (or JC1 + A21 combo) would sound closer to the Luxman than the Rotel would.
@atownkeep I do not understand the concern about option 1 you have.

When you say "Sound is going to sound different from the rears and center than the front left and right
Thoughts: This seems like the best solution because my 2 channel listening will not be compromised" what you mean by "Sound is going to sound different?." 

Different compared to?. Don't you have room correction?. It should adjust the right / left SPL level due to the gain applied by your Luxman AMP?. Won't it?, apply HT bypass and calibrate then you are good.

Won't this work?.

I do not have room correction at this time despite several people telling me to download Dirac. 

My concern is that if I put a Yamaha, Onkyo, Marantz HT Integrated to power center and rears the sound produced by it will sound different than the the left and right speakers being powered via Luxman. 

Or if I went with separates with HT preamp and a 3 channel amp that again the sound would be different. 

I could be way off base and it may be fine. 

At this time I am thinking that buying two more M-900u one for the center and 1 for the back and pairing it with a Krell HT preamp may be the best way to go. However that is another 30k and I do not really want to drop that amount of coin for just HT. 30k buys a lot of trips to movie theater!

Or I am going to go 2.2 HT and just keep on rolling.  
Doesn’t your avr have distance or SPL setting per speaker ?. You could use that to compensate. I think at a crude level this is what room correction will automatically calibrate for you among other things perhaps.

My Jeff Rowland 625 S2 amp drives my Monitor Audio PL500 II front speakers. My ATI AT523NC 3-channel amp drives my center and rears. I'm not doing "critical listening", so when I watch television or a movie I don't notice a significant difference. When I'm listening to music(2-channel) my ATI amp and AV preamp are turned off.
@ricred - I think those amps are relatively close in sonic signature.  They are not extremely warm and not extremely fast, but both pretty neutral.  If you had a radical mismatch, I think you would notice more differences.
@atownkeep - I hear you.  I don't think trying to get a AVR Receiver or Integrated would really be the answer here, as they all have definite differences.  I think it's much better to look for a set of amplifiers that would closely match your Luxman amps.  Then the choice of HT Premp/Processor is not that critical, since all channels would be somewhat matching.  Since HT movies really need excitement, I would probably recommend a very high resolution HT Processor for your scenario.  The warm Luxman/other amps would sound too dull with a warm HT Processor such as Marantz or Bryston SP3 (yes, the SP3 is really laid back).  I am totally not a fan of room correction, although many other people are.  Both the Krell Foundation 4K and Anthem (either D2v 3D or AVM60) have their own auto-eq and room correction.  They are both high resolution processors and support 4K.  The Classe Sigma SSP Mk II is also a good high resolution 4K processor, but it does not have auto eq or room correctoin.

That is kind of why I put forth the idea of getting a Parasound amp - it is on the warmish side, but still has good slam.  The A31 is probably a great price for a solution ($3200 retail).  Other amps could be like Aragon (they have both a Iridium monoblock a 8008 stereo).  Or something like a B&K, but they are very old.  I'm sure there are other warmish sounding amps.  You could try posting that question in the "Preamp/Amp" thread as "recommend an amplifier that sounds very close to Luxman 900u and offers both a monoblock and stereo amp".  The list of manufacturers that would offer a 3-channel which also has that warm sound is very small.

Maybe an idea would be to pick/buy your HT Processor and then try a Parasound A31 amp from Audio Advisor.  They do have a 30-day return policy, so if it's not close enough sounding, you can return it.
I use a simple XLR switch (DIY with high quality parts) to toggle between my 2ch tube gear to LR speakers, and use a classe CT800 processor, which by the way does digital music fantastically. I have an Oppo 205, that has 2 HDMI outs, one for audio (so I am not a slave to HDMI changes) and the other 4k direct to screen. Unless I want Atmos etc, I have no need to change.

Sorry, nekoaudio, but I disagree here. A large power supply in the amp is very important, yes, but the sonic signature and how it reacts to signal/load is another important factor.
@auxinput Apologies for being unclear.

I was only trying to say not to shortchange how much power and drive capability you'd want from the other speakers that are only in use during home theater playback.

My comment about ignoring the sound quality for the purpose of that paragraph was meant to focus what I was trying to convey on that aspect. Of course there are many other factors in play that are still important to consider including sound character, size, aesthetics, system synergy, etc.

I only intended the Bryston to be an example.