Using Sound Valves tube pre EPL function.....

I am trying out a Sound Valves VTP-100 to see how it compares to my Sonic Frontiers SFL 1 Hybrid Line Stage. I feel the Sound Valves has a richer sound and more of the tube signature I am lookinf for but I was hoping that the "External Processing Loop" would be similar to a HT bypass and enable me to hook up my Rotel 1068 Pro into it to avoid using a switch box wich up till now I have been using to switch Pre amp's for the Main front speakers wich are shared in a dual use system.
Can this Loop be used the way I had hoped? I know it can work if I use the Rotel as a line level volume for the center and surrounds while matching the tube pre level for the mains but I was hoping that I wouldnt have to do that, is it possible? Thanks
I believe the EPL was used to connect an equalizer or dbx type box. Hafler and several other manufactures placed this function on their preamps. The new digital gear may not be comptiable with the VTP 100.

On the sound of the VTP 100 vs the SFL 1 there is no comparison. I owned the VTP 100 and another one of those Dynaco/Hafler/Soundvalves tube preamps and to my ears they never performed like the better equipment. They were fat sounding and had a very fat bass response and they were rolled off on the top end. They lacked detail compared to the better (more expensive) units. Ying and Yang dark and bright comparison. Personally, I thought the PAS 3 sounded better than the early sound-valves preamps. I haven't heard the PAS IV, etc but I hear it sounds much better than the VTP 100 or VTP 100i.

For what it's worth that's my 2 cents on the issue.