A bit late to the dance...
Firstly, apparently there is not much Klipsch love here - probably fueled from folks who at most had 'auditioned' some of their earlier PRC-made fare in the open in a Best Buy, etc. My first exposure to the marque was via the K-horns in 1971 - wow! Sadly, even their entry-level (US-made) Heritage series, the Heresy iii, is well over my spending limit... I had to try a pair of KB-15's, the predecessor to the OP's listed R-15M, when they dropped to $129/pr
... wow! Last November, I took advantage of the Amazon BF sale - and got a pair of the R-15M's for a song. I A-B ed them with the KB-15's - the newer horn driver sounds at least as clear as the earlier KB-15's, except for the fact that cymbals & piano notes sound as if they are 'suspended in air' - a subtle improvement. Compared to my excellent, but inefficient, NHT S1 2.1's, their high end sounds different - not necessarily 'brighter'. I prefer their sound - but then, I am a few days shy of turning 68. I drive them all with my 50 Wpc stereo CD system, composed of an Onkyo TX-8020 stereo receiver and C-7030 CDP (98% music!). The rear-ported Klipsch speakers have 8-10" of clearance to a wall.
My NHT S1 2.1's were a shocker, audio quality-wise. Size-wise, they are the same physical size as the R-15M's, but employ a 6.5" LF driver in an acoustic-suspension enclosure vs the 5.25" LF driver in the R-15M and Elac B5, both bass reflex designs. The NHT's are ~86dB SPL, while the Klipsch R-15M reports 94 dB SPL - and you can hear that! I'd offer the NHT's as a suggestion, as my experience with them has been great - except for the current Amazon price of $350/pair vs $199/pr
for your B5's, which are oddly as inefficient as the NHT's! Enjoy your new speakers - I am certain that you will be happy with them!