I did this exact application with a ARCLS25MK2 about 3 years ago. I used a Theta Casablanca home theater processor, and fed the left front channel and the right front channel outputs (via XLR cables) from the CB into the "By-Pass" inputs of the LS25MK2. I then, obviuosly, connected my CD player direct to the ARC preamp, and from the LS25 out to my monoblock amps, and finally to 2 front speakers. On the remote for the LS25, there is a button that i recall read "Pass Through", as in to pass an incomming signal (from your HT Processor) through and out the preamp. You hit that button and it switches inputs on the back of the pramap to the Home Theater By Pass Input and simply routes that input out the main outputs of the preamp with out touching its volume. You HT Processor still has complete control over volume.
If Music is your main concern, I am going to go out on a limb and make the statement that with out question, if you have a good cd player (high end DAC's), you will always get better sound running it through an analog 2ch preamp versus running it into ANY home theater processor, regardless of cost. I also really like the ARC LS25MK2, but there is 1 potentially big drawback if you really care about home theater. When running home theater through a 2 channel analog preamp, most preamps, including the ARC ls25mk2, will be processing to some minor degree the signal and thus degrade it. With the ARC LS25, home theater front right and left DID sound worse running throught the ARC. Not horrible, but just not as good as running from the processor directly to the amps. I easily lived with it because my only critical concern was 2 channel, but you can easily hear the difference between running the processor direct vs. running it throught the LS25MK2. On the other hand, my 2 channel setup sounded marvelous comming off the LS25.
FWIW, 12 months ago i replaced the ARC with a VTL7.5, and ran it in the same hometheater by pass mode. With the VTL, I could not distinguish a difference in home theater. I guess for 13K, it had better darn work well!!!!!
If Music is your main concern, I am going to go out on a limb and make the statement that with out question, if you have a good cd player (high end DAC's), you will always get better sound running it through an analog 2ch preamp versus running it into ANY home theater processor, regardless of cost. I also really like the ARC LS25MK2, but there is 1 potentially big drawback if you really care about home theater. When running home theater through a 2 channel analog preamp, most preamps, including the ARC ls25mk2, will be processing to some minor degree the signal and thus degrade it. With the ARC LS25, home theater front right and left DID sound worse running throught the ARC. Not horrible, but just not as good as running from the processor directly to the amps. I easily lived with it because my only critical concern was 2 channel, but you can easily hear the difference between running the processor direct vs. running it throught the LS25MK2. On the other hand, my 2 channel setup sounded marvelous comming off the LS25.
FWIW, 12 months ago i replaced the ARC with a VTL7.5, and ran it in the same hometheater by pass mode. With the VTL, I could not distinguish a difference in home theater. I guess for 13K, it had better darn work well!!!!!