Wayne Parham Messages: 18786 Registered: January 2001
Illuminati (33rd Degree)
A Bose 901 creates a sound field that is 90% reflected. A horn creates sound that is 90% direct. They are two different approaches and I wouldn't combine them.
In my opinion, directional sound is best for mains and reverberent sound is best for surrounds. So I'd use some horn/waveguide speakers for your mains and repurpose your 901 speakers as surrounds.
But that's answering a question you didn't ask. To answer the one you did:
If I wanted to add some sparkle to 901, I'd probably add dome tweeters on each side.