Considering a POSSIBLE replacement for speakers. Opinions?

Great pair of monitor audio pl100 mk ii for sale on us audio. 2500.00$. 

You have a lot of good choices. The Magnepan LRS with a pair of subs (especially the GR Research/Rythmik OB Sub) is a good one, the Maggie-killer Eminent Technology LFT-8B an even better one. VPI’s Harry Weisfeld considers it to have the best midrange he has ever heard, regardless of price (I compared the LFT-8B to the MG1.7i---no contest). But both those options require spacing of at least 3’ from the wall behind them, 5’ even better.

For a monitor plus sub(s), I know what I would do: Posted just today here on Audiogon is a pair of GR Research NX Studio Monitors, custom made by a private speaker builder from the GR Research kit (the only way the speaker is available). The seller has priced the speaker at the cost of it’s parts, so not only do you not have to build it yourself, the cost of him doing it is.....nothing! Add a pair of subs (again, the OB sub would be optimal), and you have a really, really good loudspeaker, at a very modest cost. But this speaker also requires 3’ spacing, as the NEO3 magnetic-planar tweeter is employed in open baffle/dipole fashion.

A pair of used Magnepan MG-20 are worth considering...but only if you like music. 

jjss49 
From the Underwood website re LSA-20 speakers

"the very fair return policy is a 10% restocking fee and shipping costs back to Underwood Hi-fi, Inc."

You should try the new monitor audio gold 200s or 300 generation 5 they sound phenomenal. Also I guess it would be good to know your budget