This is actually a pretty simple one to calculate. The Equinox traveled (approx) 10,000 light years in two weeks which means they traveled at an (approx) average speed of 260,000 times the speed of light.
Using at the warpspeed calculator on Memory Alpha (which in turn references the Warp Speed Diagram shown in the TNG Technical Manual), we can determine that the Equinox traveled at a sustained cruising speed of (approx) warp 9.99992, several orders of magnitude above Voyager's top speed of warp 9.975.
It might interest you to learn that since the nominal top speed of the Equinox was Warp 8, and since each entity only gave the engines a ....
point zero three percent [boost] for one month
... in order to reach the sort of high warp speeds they've been using, they would have had to kill (approx) 66 of these creatures per month for 24 months, nearly (approx) 1600 in total.