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 $500 used.
Thank you in advance.
128x128uberwaltz
At that price the Polks seem interesting. As I have previously stated I already have too many speakers or I might try a pair. 
i like the b&w 686,you can get them used for less than 250$. 
i auditioned them next to the 685 who got much better reviews at the time but i prefered the 686 because they sound sweeter and less forward. i used an old arcam delta  integrated with them and it was a great match ,they were ok with rotel and nad amps  but nowhere near the arcam.  they need at least 75wpc though they are quite small.
there are refurbished ohm walsh e2 for 400 now on their website (outlet)they have a 120 day trial! and 3 years limited warranty.you can probably get some great used  kef,infinity or dynaudio bookshelves for that price as well. what amp?
Nice suggestions all for sure.

I did buy the Vienna Acoustics Haydn as they were immaculate and even set up in very poor location at his house they really sounded good.

Will be giving them a long road test tomorrow.
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