Adding Home Theater To 2 Channel System


I have a two channel system that I am very happy with located in a dedicated listening room.  I am considering how to add home theater without giving up the two channel sound that I enjoy.  My main speakers are Avantgarde UNO’s (horn speakers - 18 ohm, 108 db sensitivity). Avantgarde does not make a center channel speaker.  I assume that I will have a problem matching any box speaker center channel speaker with the Avantgarde - my worry is incoherent sound.  Is this something I should worry about?  Are there center channel speakers that might be a good match (I have been unable to find any obvious candidates ohm/sensitivity match)?  Is it likely that I will need to find a new set of front speakers from the same brand as the center speaker?

The rest of my setup: Pass Labs XA 60.8, Audio Research Ref 6 preamp, SME 20/2 turntable, Lumin x1 streamer, Ayon CD player, REL 812/S subs (2)
chilli42
Tried it and it was one compromise after another. I ended up just adding an entirely separate system for the ht piece. Two channel has been kept as is with no connection to the ht.
Hello,
Wow, This got a lot of responses. Just like when someone thanked MC for something and all hell broke loose. JK. I think MC is funny as hell. You are correct about the REL LFE input. You can use the speakon or RCA/XLR connection for the two channel and set up the L.F.E. Input for HT which has its own level control. So you are good on subs down to 28hz. Set the level at 10:00 position instead of 12:00 per the directions during the setup mode so you can add a little more when finished. Also, change the subwoofer distance in the Denon virtual setup by adding 10’ to what it truly is. Actual 15’ from you becomes 25’. You will be amazed. 
Denon made a model called the X3600H and then the X3700H which went to 8K but more importantly to 120 refresh rate at 4K. The amazing benefits besides the video is that you can divert the two front channel amps and use them for surrounds if you have your own front amplifiers like your two channel system. Good on the wallet too. 
When listening to surround sound 65% of the sound comes out of the center channel, 25% comes out of the fronts, and 10% comes out of the rears. You can have a fantom center if your two channel is killer.
I have played a full movie for people on just my two front speakers. My front speakers also go down to 25hz. It can be done. You might want to start with the surround receiver and some surrounds and go from there. Just remember the more speakers you add the more you have to control the sound. 11-13 speakers is a lot of sound to control. I say 5.? Channels unless you have two rows of seats then you go to 7.? to fill in the gap.  No TVs unless you will cover it up when listening to music. The glass is a sound killer. Another ideas is a virtual frame screen painted on the wall and a projector of your choice. 
Look at the post above for screen projector ideas. I do like the drop down acoustic transparent screen. It lets you go big. I might do this next. Be careful with Klipsch/JBL speakers as a match. They can dip down pretty low in the ohms department. Even below 4ohms. I say go with 8 ohm speakers for the center and surrounds and don’t worry about matching the horns. You might want to look at KEF speakers. The Q driver system works very well at even dispersion. I have seen their new $600 Q150 speakers which would work great for surrounds go for $300 a pair. Cross them over at 110hz and let the subs do the rest. What most people do not realize is the amount of DSP a surround receiver has will make a silk dome sound like a horn speaker. I have a Sonus Faber Cremona center with a silk dome tweeter matched with my aluminum tweeters on my mains. They sound like one huge speaker which is what you want. By using less amplifiers in the receiver you actually get more watt output to each speaker. 5 speakers pushed vs. 9 speakers pushed can give you 25 more watts per channel. Later you can get a dedicated home theater sub or room shaker that will go past 20hz and keep your RELs just for the two channel. HSU or SVS are good for that but I prefer JL Audio. Finally, Upgrade the power cord on the surround sound receiver. It makes a huge difference in the sound and performance. I like the Nordost Blue Heaven or Puritan Classic Plus. Seriously, Amazed! Sorry for the long post but this can get expensive and you can make a lot of mistakes. Start with, Denon-$1100, screen- $1000, projector-$$? and surrounds-$300 and build from there. Better yet look on Craigslist or AGon for a cheap surround speakers. 
I'm in the two separate system camp
In my credenza l have my VAC tube amp/ARC tube pre amp and my Emotiva XMC-2 16 channel!! Processor & Anthem MCA-5 that I've owned forever  I have two set of main speakers, center speaker and two SVS Sub woofers My rear speakers are wireless  l just turn on the system that l want to listen too 
You can do without a center channel but HT is carefully developed to have dialog specifically coming from a center. Because the frequencies sent to the center channel are relatively easy to produce so you can go with a very different design of speaker for center.
And quality or price is not critical-within reason.
A very interesting choice would be the MBL 111 single speaker currently for sale on AG. I think that is the model #. It is the small entry level one. It has been for sale for quite a while for about $2500.
Surely he should take a decent offer. That would be a super interesting center to combine with your Unos!
A completely separate system except for the Unos is best.
I don’t think it would be a problem to run additional speaker cables so that the Unos would have two pair of cables each.
Certainly, your choice of TH components depends on your wallet.
I have seen HT done with tubes but SS is most common.
Most important is to have the same amp for the RL and C. Best is a 5 channel amp and a good processor. What I would get is an older top line Meridian processor. You can pick one up for a fraction of their original price. Features will be more than you will need.
And getting an older pair of Meridian powered speakers would be great. Then you will need a 3 channel amp or 3 mono blocks.
I would get (unless you already have on) an OLED TV. Sony is best.
At least 65” but I would get a 75”. Going with projector and screen is tricky and probably double or more. A projector will give you about a 100” picture but not necessarily a sharper image.
In any HT, the processor is the most important and what you build your system around. For SQ and functionality, I love the Meridian. Especially since the older ones are still perfect for a basic 5.2 system. Think your subs can also take double cables but I think a Meridian also has two rca sub outs. I just want to emphasize that an older processor’s features will be all you need and more. The top line one is great but a G65 one can be had for about $1K (think the MSRP was over $5K!). It is also excellent. Mostly less features that you will not need.

HT is also designed to be backwards compatible. That is just how it works.