What speakers go best with a Mcintosh MC240

I am running a McIntosh MC-240 with an MX-110 Preamp/Tuner. Both are in excellent shape and have been retubed about 75 hours (of use) ago. (Amp also has new caps). I have a pair of B&W Matrix 805's but the amp doesn't seem to have enough power to drive them properly/loudly/clearly and they have been moved over to my home theatre. Currently, I am running a pair of Klipsch Fortes with the amp but the sound is just so-so. I have read some forums where a SS amp is used for the low end and the tube for the hights but don't really follow the point. Any suggestions would be helpful.
Thanks!!