Surround Speaker Question

Thank you all very much. I am using a Krell HTS preamp, Sherbourn Power, Faroudja DVD/CD, and Martin Logan Source speakers for main

As usual, there are going to be some that read to much into it. The OP wants a suggestion on surrounds without giving any info on the rest of his speakers.
Myself, I feel any good dynamic speaker that will convey background info will do in a normal HT setup.
If he was so critical, he would already know to buy the same brand and model as his fronts.

I must add that the BEST surround speaker would be the same speaker as the fronts.
But I gather that the op is looking for an alternative speaker that will work well.

I think th best surrounds are from the same manufacturer as your fronts. That way they are similarly voiced .

i'd consider your movies (assume that is why you have surrounds) and then consider your budget. personally I only have a couple movies with enough content to worry about surrounds and consequently I think I overspent on my rears. YMMV. Mind I have movies with content but only one or two where the matching to the fronts makes a difference utilize my quality rears.