The 525 is not like the 2500. The 527 is more like the 2500. I've not used the 527 or the 2500. I believe the the 525 was API's answer to the LA2A......sort of. It has a really nice built it de-esser. It took me a while to get the hang of this compressor to be honest which was disappointing because anything API I've ever owned was an instant love fest. This one took a little while but now I really love it. I plan on getting another for my for things like my "solo" channel which I tend to treat like a vocal.