Yes, I’ve seen Paul’s comments on that question before. In fact, there’s another thread going on the forum (which you’ve probably already seen or even participated in) in which Al in particular commented that every time he tried his DACs as preamps and was pleased with the results, but then reinserted his actual preamp in the chain, he was surprised at how much better things sounded with the preamp. Unfortunately I just took a quick look for that thread and couldn’t locate it.
EDIT: here’s that thread: Preamp suggestions? - #12 by aangen
For me, I’ve never been able to avoid using a preamp because I have an analog source I need to be able to hear. Maybe if the backside of the boxes was more accessible I might be like you, and switch between setups as needed. But that’s not going to happen in this listening room, which is likely going to be my last. At least until the Big Downsizing for the retirement home, when the analog stuff (and probably even the silver discs) will have to be jettisoned in favor of streaming, and the facility’s piped-in “medication time” music. 