How to merge my 2 Channel and HT Systems?

OK, I have downsized to a smaller condo and no longer have the luxury of a dedicated music system in one room and a full HT setup in another. I really would like to keep at least my Plinius SA 102 to power my Joseph Audio RM25si's for music (Thorens turntable, Theta Miles CD player, and maybe FLAC streamed over network) while using my preamp (Anthem) for both and power amp (B&K) to power the rest of the system when listening to HT. Is it possible to merge my two systems so the Plinius drives the Joseph Audio's for music and HT and the rest of the system kicks in for HT?
Do you have a sub?
Ummm. Is the Anthem a stereo-only preamp or is it a MCH preamp-processor? If the latter, just connect the L/R output of the Anthem to the Plinius and the other Anthem outputs to the B&K and sub. If not, does it have a HT bypass feature? This feature is pretty common these days.

I used to have them murged and have changed back to two separate systems in the same room. MY stereo is the long axis, and the Plasma and surround are the short axis across.
Works fine for me.
The only way to merge that seems to work at all is to use an integrated amp with HT bypass. Otherwise the 2 channel is severely compromised.
i tried a merge and it failed miserably. i still keep them in the same room/rack but also keep them separate/independant of each other.....all the way down to the power supply. MUCH better results for me.

merging the two will be one big compromise for your 2ch set-up.

...very hard to do. The best way is to have 2 separate systems.
I use a MANLEY Skipjack. This allows me to use my two channel preamp (output to Skipjack) for two channel sound and my Anthem D2 for HT. (front left and right output to Skipjack). Skipjack outputs to my two channel amps. This also allows me to incorporate my sub only through the D2 (the sub output was adjusted using the ARC system)into my two channel set up as well. This gives me the best of both worlds.The D2 is not a very transparent preamp for two channel IMO.
This also allows independent volume adjustment to the sub when listening to two channel which is very cool!
It can be done, the biggest problem is what is between the two channel speakers. If your screen is wall mounted you're in business. Once I went to a FP and placed the screen on the wall, getting rid of the obstruction between my L/R speakers, a whole new world opened up.

No matter how well you approach it, optimal L/R speaker placement is different for HT and 2 channel. So a combined system will have compromises. But once the L/R speakers have room to breathe the compromise is modest.
I have an 2 channel set up (cd player -> dac -> preamp -> 2 channel amp driving left and right; sub takes low freq thoght he preamp sub out) that is "connected" by HT bypass to a NAD multichannel reciever (does all video processing and multichannel audio and drive center and rear speakers). So, when listening to 2 channel, no compromise as nothing runs through the HT setup. With HT, the amp is contoled by the volume control on NAD (through HT bypass)
Does your Anthem has 7.1 output? If it does, I would connect the LF and RF to one of the input on your Plininus. This way, you can use the Plinius in both 2ch and HT. If the Anthem does NOT have the 7.1 output, I would connect the 7.1 LF and RF outputs from your DVD/Bluray player to the Plininus. Same concepts.

I do it as follows:

Surround processor to the "unity gain" input on stereo preamp. The sub is on the LFE output from the processor. I run two channel as full signal with no subs. For HT, I hit one button on the preamp remote to change from the two channel input port to the "unity gain" port.

Wyred 4 Sound sells a stereo preamp with an even easier HT bypass that lets you run the subs in both modes. I only changed from it because the BAT preamp sounded better in two channel.
Moto Man

I have done this for years. I have the stereo outs from the processor go into a tube preamp. The tube preamp has two sets of outputs, one connected to the multichannel amp and one connected to tube mono blocks. The preamp is set to unity gain when listening to surround sound. When I listen to stereo you do have to switch speaker cables from the surround sound amp to the tube mono blocks and make sure the surround sound amp is turned off as my speakers do not have two sets of connectors. To some people this may be a pain in the rear but works for me.

I really do not have another choice as the room is too small to have two separate setups.
I've done it successfully. You will need to spend some money on a really good pre/pro that won't compromise the sound. Krell HTS 7.1 sounds really good as an analog pre-amp, so that's the route I went.
I looked up the Anthem Preamps and it looks as if they all have a loop through or unity gain so an external processor can be add and control the volume. As long as your intergrated A/V pro has either a line level output or you are using an A/V processor with seperate amps you should be fine. This would be easier if you include the MODEL numbers of all your equipment so manuals can be looked at.