OP,
If the new cost of a REF6SE puts you off think about a used REF5SE… or even 5. You will get most of the sound, for much less money. I am sure the average life of an ARC preamp is over thirty years.
I upgraded from an REF5SE to a Ref6se… but mostly because I upgraded all my other components to contemporary REF. Yes, the 6SE is better than the 5SE.. but better the 5SE than something else… my belief. I had a 5SE for nearly ten years. It was never the component getting in the way of better sound.