ARC LS 25, 26 & 27

I have a Denon AVP and a Mark Levinson 433. While I'm currently running my vinyl through the AVP, it has a "pure direct" option to bypass all the digital processing, I'd like to ungrade. The Audio Research LS27 has a processor input which bypasses the gain stage. So I can place it between the AVP and the power amp. This allows me to bypass the LS 27 when I'm listening to surround sound and, more importantly, will upgrade my pre amp for two channel vinyl.

What I'd like to know is when ARC began offering this in their line stages. The LS 25 and 26 have a processor input, like the LS 27, but I can't seem to find out if it's a true bypasse. That is, does it bypass the gain stage or not?

Does anyone know? Do I have to go to the LS 27 to obtain it?
I am not sure about the LS25 but the 26 and 27 have Unity gain. They bypass the volume circuitry but still send the signal thru the output stage. Give AR a call they are real helpful folks and can answer with more accuracy.
Yes it does bypass the gain stage. I think ARC has the function since LS-2. I had the LS-1 and it did not have that function. I then went to LS-3. But can't remember if it has it or not. My 3rd pre was the LS-2b Mk II, and it definitely has that function as I had my system set up where I was using that mode to run my HT set up. My next and current pre is the LS-25. But I decided to separate my audio and HT systems completely, thinking that burning 4 NOS tubes while watching movies (and not even getting any benefit out of them) would be a waste.

Frank I feel your pain. The LS25 MK2 wouldn't be as bad as it only uses two, very robust tubes. But I prefer the MK 1 and the very concern you mention is holding me back. It's to bad to have to turn the LS on to engage the bypass.
Can you guys suggest an AR line-stage preamp without a phono stage? It can be something current or older to vintage.
The LS denotes Line Stage, meaning that it is not a full function preamp, as none of them has a phonostage. Only the SP line has built-in phonostage. So take your pick. :-)