It really depends on how well the line out is on a unit. My Esoteric K-01 using the line out function is superb. It really shows how good the K01 is. But I need the preamp to power my sub which I cannot do without it. So a preamp gives you lots of flexibility, if I did not need that I could leave with the K-01 directly to my amp. In fact if I had full range speakers I would not need the sub and I would use the line out of the K-01. It's world class.
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?