for that room size I'd definitely go for bookshelves, rather big and high performing ones, with relatively small drivers that are fast so they dont pollute, and that can be adapted, tuned to your room and/or liking using back switch and bass plugs. No need to go second hand at that price, just get the XTZ Divine Delta brand new and prepare to learn that real high end performance is available at more reasonable prices. I own several speakers, some costing $35,000, and I also own several XTZ speakers.... My other choice would be Tannoy Legacy Cheviot for an extemely energetic, lively, musical sound. All these will pair perfectly with your Plinius.
Good Used Speakers ($8K-10K) For A Little Listening Room
I know that this is a tough one, because speakers are so subjective. My dedicated 2 channel listening room is only 10ft x 10ft. I listen to mostly jazz and rock. I currently use a Plinius SA100 Mk III (recapped and upgraded) driving Joseph Audio RM25XL's. I'm thinking of upgrading and was wondering what speakers would be a good upgrade for a small listening room. I like the Joseph Audio sound, but want more. I was thinking of Pulsars or maybe Perspectives. First, is my room too small for floor standing speakers? Second, what other speakers in the $8-10K range used would be a good fit in a small room?