matching speakers to krell 300i

Hi - I would appreciate any suggestions for matching a Krell integrated amp (300i) with speakers.  Currently I'm listening through a pair of PSB Stratus Silveri's rated at 4 ohms.  The rectangular room is roughly 12 by 18 feet.  I'm happy with the Krell and the PSB's sound good, too - with the exception of some clipping which is new.  I suspect I could uprade to a more efficient speaker in the 2000. - 4000. range and improve my listening.
Also, I use a Rega P-5 and SimAudioMoon CD-1 as sources, Cardas interconnects and PS Audio in wall power conditioning with PS Audio power cables.
THANKS for any suggestions you have!
uhclem