If you are after a holographic soundstage, IMO you are barking up the wrong tree to focus on speakers. The Plinius is not goin to yield that no matter what speeakers you pair off with it. I would recommend you go out an listen to a few tube-based systems if you are after a holographic soundstage. SET amplification would yield the most holographic soundstage. OTL would be a great candidate as well. Either may involve reconsidering both amps and speakers. Given the expense, I'd suggest you go give them a listen before taking that plunge. They would sound quite different from the SS you are used to.
Marco
Marco