You've done it so do you prefer the sound direct vs your preamp? Your preamp being some 38 years old may be in need of a refresh and certainly a retube as suggested above.
Should I eliminate my preamp?
I have been using my Audio Research tube preamp and Bryston amp to drive Magnepan speakers for years. Recently I added a Oppo blue ray player to my system and connected directly to my amp using the balance cables. The reason was to eliminate the signal having to go through another piece of equipment before it hits the amp. Am I wrong or what am I missing?