High value, giant killer speakers?

What speakers have you heard at any price did you find are fairly priced or a great deal and competed with offerings much more expensive (2x, 3x, 4x etc)? 
My room is quite large it's hard to get proper spls. Prior to owning my EP KCIIs I had a love/hate relationship with Magnepan 3.5Rs driving it with W4S MC 250/500 class D amp using the 250 on the ribbons and the 500 on the bass panels, but it never was seamless, and always too bright. I even tried a Parasound A23 (class A/B) to no avail. I sold the maggies and the W4S and bought the EP KCIIs with which I have used the following class D amps; EP 100.2SE (monos), Audio Alchemy DPA 1, PS Audio M700s. Each sounded different, but although very good. One of the missing musical ques was solid bass, unless I used my 2 SVS powered subs. Now they brought the bass but were impossible to blend correctly, muddying the music. I wasn't hearing what I knew was on the discs.

After a month or so of investigation into the EVS 1200, I ordered it expecting it to allow me to eliminate the subs. The EVS 1200 has the newest IcePower 600w modules + lots of tweaks by Ric Schultz, who has been tweaking products for many years. It is priced within the range of the other amps, but $700 less than the M700s @ $2200 and comes with a 30 day money back guarantee. Nothing to lose, tons to gain

Fast Forward 50+ playing hours (now about 100) I disconnected the powered subs as I have much better cohesive bass than with the subs. Still the KCIIs only go to about 42Hz, which is plenty deep for most music. These speakers NEVER sounded so good. That said, my room is quite large and I am anticipating a pair of 2.8s arriving by the end of this month

Moral of the story, both matter
@213runnin that wasn’t my experience at all. Plus numerous threads of them going into protection mode on semi-difficult loads.

At what starting point does a loudspeaker have to be to be a 'giant' killer? Obviously the LRS is, but can a speaker that costs $9000 be deemed as such? The new Elac bookshelf loudspeakers as heard at the RMAF this year certainly are slayers to my ears.