Does the Spendor S8e invert phase?

Hi, I have been listening to a pair of Spendor S8e's and noticed that the transients didn't sound as crisp as my Vandersteen 1B's (which aren't exactly the most detailed speaker).

However, on a whim, I swapped + and - on the speaker cables and it seems to have improved the sound. Has anyone else had this experience with this speaker?

I had also heard that people with tube amps like the Spendors better than those with solid-state amps. Since many tube amps and/or pre-amps are phase-inverting, I wonder if it has something to do with this. Thanks.