What Audio Research tube pre amp ?

I am looking to buy a used ar tubed pre. There seems to be couple dozen models in my price range (up to $1500) . They all seemed to be about the same price new throughout the 80's through present .roughly $2500 new. I do not need a phono ,so should i only be looking at the linestages ? are the sonics pretty similiar for all these different models. I am using a bryston 4bst driving magnepan 1.6 . any thoughts would be appreciated .
I had Maggies and several Bryston amps over the years.My pre of choice was an Audio Research LS 15 and it was a very good fit.Flip me a pm for more specifics if you're so inclined.