Advice on buying a used speaker up to 3k

You all here on agon helped a lot in buying an amp (went with pass labs xa30.5 with you advice and my research) under 3k that I want your help again!

I love what the pass labs amp has brought that I have an upgrade inch again. My other components are an NAD m51 dac which has a 35 bit volume control and hdmi so it seconds as the preamp too.

My source is an oppo 103d which I use strictly for digital files and high resolution downloads used on a the flash drive on the oppos input. Also like dvds and blu rays on the system.

I have some Kef 104/2 that I really dig but I believe I am missing some higher frequencies with some of the new tweeters technology thats out. I have been impressed with what I have heard about the Raal ribbon tweets but there may not be a lot of choices at the price point.

The pass labs needs high efficiency speakers above 87 db. I also would rather want a tower over monitor but am open. I may be wrong but monitors seem to not be able to sound full range or complete as I think of it???