Suggestions for bookshelf speakers that have great dynamics, budget of $500 used.


So I really do not know where to start with bookshelf speakers as not been in the market for any for ever it seems.
This is for a second system where a pair of Monitor Audio Silver 3i are currently doing duty.
Room is largish and open but ultimate sq is not the aim as it is occasional use only, but when I do fire this rig up I usually like to play fairly loud.
Sources are many, fm radio, cassette tape, vinyl and streaming.
I have plenty of horses to feed them so even inefficient models can be considered.
Prefer to buy used as big savings to be had obviously and already broken in.
So suggestions around a maximum price break of $500 used.
Thank you in advance.
128x128uberwaltz
Polk Audio is discontinuing their flagship LSiM line, and as a result they are unloading existing inventory at greatly reduced prices. You can get a pair of the LSiM703s for $600 new on Amazon (originally listed for $1499). They are unusual for a bookshelf in that they are a true 3-way speaker.

Stereophile reviewed them positively several years ago and confirmed that their -3 db point was 55 Hz. It is a 4 ohm speaker with 86db sensitivity.
https://www.stereophile.com/content/polk-lsiiim703-loudspeaker

At that price the Polks seem interesting. As I have previously stated I already have too many speakers or I might try a pair.