Monitors or floor-standers with Bryston B60SST?

I am the proud new owner of a Bryston B60R-SST amp. Now I want to upgrade my speakers.

About half the time I listen to chamber music (Bach, Haydn, Mozart, Beethoven). Choral music, orchestral works, and pop music account for about 40 percent of my listening. Jazz, folk, world, etc., fall into the final 10 percent. I have a medium-sized room, and I prefer to listen at moderate volume.

I started out thinking I should get a stand-mounted monitor like the Paradigm Studio Reference 20 or the PMC TB2. But for about the price of good monitors and solid stands I can get a floor-standing speaker like the Spendor S5e or PMC GB1. My concern is that the B60 might not handle the larger speakers as effectively as the monitors.

Any opinions on the ability of the B60 to drive larger speakers? How about the speaker choices? Have other recommendations? Thank you for whatever advice you might provide.