ARC LS 25 Mk 11 Bypass

Hello
I do this same thing with my sound room. I take the output from my Meridian HT system, front left & right to the proc input on the Ref3 then from the Ref3 output to the amps, This lets me be very flexable. This allows the Ht or Stereo to control it's own volume. With it this way you can also send the digital output from your equipment to the HT system & all the analog outputs to your stereo preamp. Then you see which sounds best to you and use the system that way. When you have people over you can use the HT and send sound to all speakers also.
The only thing you should do then in my opinion is optimize the room for 2 channel and use the digital abilities of the HT processor to adjust the HT part of the system. You also might want to cover your screen even one that is flat, with something when listening to 2 channel cause that way you will get a better imaging & a better sound stage between the speakers.

Billbench & Oneobgyn
Yes it does alter the sound, it has to because the signal passes through the tubes, but the Ref 3 is so good that I think it gives it a better sound stage. I have a Meridian G68 for HT.
I had a VAC Standard LE Tube Preamp by the way and it just passes the signal through wiring and not the tubes, it can be off while you are in HT mode.
AND tlg.
The stereo preamp that has HT mode either sets the output volume at a constant and repeatable level all the time or just pass the siganal straight though via wiring. Your HT is controlling the volume as if the stereo preamp was not there and it can also be calabrated correctly.
Also this stops you from having to set the volume on your stereo preamp. If you do not set the volume exactly same way everytime any calabration you have done will not be correct. A HT not calabrated is a waist off time and money.
As with most analog volome controls, because they work with resistance, being off a little can mean alot so you are much better off this HT passthrough.