How times have changed. Thirty years ago such speakers would have been called 'miniatures'!
No, even by today's standards, these Klipsch Fives are small bookshelf/standmount speakers and are indeed far too small for your room, even with a sub and a high pass filter. You can't defy physics and a 4.5" bass.mid driver can only move so much air.
An example of a large bookshelf/standmount speaker would be:
Active 2-way near field reference studio monitor Woofer: 8 "woofer (203 mm) 70 W with Kevlar membrane, Amplifier: 150W RMS bi-amp Class A / B power amp, Maximum level: 114 dB, Crossover: 1900 Hz, Further sound adjustments: Acoustic Space, Frequency...
www.thomann.de
and
A powerhouse of a loudspeaker, the Monitor Audio Silver 100 stand-mount delivers incredible dynamics and serious bass from a compact cabinet.
www.monitoraudio.com
Also, whilst I've never heard the Klipsch speakers, £800+ sounds like a lot of money for small powered speakers when you can get these for under £300:
Active Near Field Monitor Equipment: 7 "woofer and 1.9" U-ART ribbon tweeter, 2x Class-D amplifier: 50W RMS woofer, 20W RMS tweeter, Frequency range: 39 - 25000 Hz, Crossover frequency: 2.6 kHz, Maximum level: 110 dB (1m / pair), Rear bass reflex...
www.thomann.de
I repeat what I said in an earlier post: if you choose a bookshelf/standmount speaker + sub, then add a high pass filter to the main speaker pair for improved audio and higher max. volumes.