Advise on book shelf speakers less then $750


I am looking for advice to help me upgrade my existing Linaeum LFX speakers monitors.  I am looking for used speakers with a price around $750 or less.  That have open, detailed with very good imaging and that are small monitors.  The living/dining room I have the speakers in is approximately 13 feet wide by 34 feet deep with 8 foot ceiling.  I normally listen to music at a low volume of around 50 to 65 dBs measured at my couch 8 feet from the speakers.  I mainly listen to jazz, blues, and some rock.  The system consist of a Threshold400a amp, a Threshold SL-10 preamp, Macintosh 7082 am/fm tuner, and a first  generation Sota turntable.  Before you start and say that I need to upgrade my components, have no interest in upgrading them.  And secondly by budget number is fixed and can not go up.  Because of WAF the speakers need to be book shelf size.  What I really want are LS3/5a made by Harbeth but they all seem to be above my budget.  Any thoughts?  
waterford
Polk LSiM 703. They definitely have their own flavor but they are a fun speaker that are a joy to listen to. The Threshold gear should pair well with their darker presentation.

I might be coming into a pair (as well as the 707) via trade-in soon if you are interested, but if you want new, Adorama has been known to sell these $1,500 MSRP speakers for $500.

The LSiM is not your run of the mill Polk product. I don’t think they ever competed at their respective retail price points but street prices make them absolute bargains.
The Wharfdale denton is a good budget BBC type monitor. They are on the mellow and sweet side of the menu. 
These:
https://www.usaudiomart.com/details/649465938-lsa1-standard-speakers/
I wouldn’t be the least bit surprised if they significantly outperform the Harbeths.

P3ESRs and LS3/5as in general are not rock speakers. Why folks keep assuming Harbeths are a great solution for any listening situation totally baffles (no pun intended) me. They are mediocre at best for rock music, and all but their 2 largest models have "plummy" bass (think cheap paper OEM automotive drivers). Epos, Tannoy, and ATC are far better options for getting the British midrange with some real punch and drive.