Mentioned by mixing engineer Michael Brauer as being used on "Violet Hill" in this Sound on Sound interview about the production of Viva la Vida & Death and All of His Friends.

Guitars: EMI Chandler TG1, Lexicon PCM42, API 525, API 5502, Roland Dimension D SDD320, Watkins Copicat

"Normally I send each side of a stereo guitar to my EMI Chandler TG1 panned left and right and coming back on the console, but I didn't in this case, so I must have felt that it sounded bad. It might have taken away from the tightness of the guitars. They had already recorded it very tightly. So instead I didn't add anything to their stereo chorus verse guitar. I also had a mono verse guitar, which I sent to a PCM42 delay set at 224ms and panned to the opposite side, and every time the guitar strums it goes over to the right. On the acoustic guitar I did what I normally do, which is to send it through my acoustic patch, an API 525 going into an API 5502. That's a great combo and I have been using that for years. It makes the acoustic guitar very natural and full and gives it great presence without it sounding processed. In this song it's not very evident, because the acoustic guitar isn't very important, but, for example, on Parachutes the acoustic is very important, and I used the patch back then. There was no insert on the solo guitar. I did have a Dimension D SDD320 chorus on it, which spreads the sound naturally, and which went to a Watkins Copicat Echo unit with a fairly short delay. Otherwise it's totally dry, no reverb, hardly any EQ. Again, it was so well recorded that it didn't need a lot of work."

Adam Young's Sky Harbor Studio contains two API 525s.

At 18:13 into his Prouction Masterclass with Future Music Magazine, Stimming mentions using The API 525 Compressor.

In this Sound on Sound article it states that the vocal was treated with an API 525 Compressor on Alt J's album An Awesome Wave

In this Facebook post, titled STUDIO 1 / ROBERT BABICZ, two API 525 Compressors can be seen.

Standing next to the API 550 in their desktop rack. Video from their studio in Berlin (visible in minute 1:40)

On his official website, Tony Anderson discusses using the API 525 as part of his studio recording setup.

Alexander Metzger, also known as Alex Butcher, is shown in a Facebook photo using the API 525, a signal processor integral to his work with World of Intros, Vengeance Sound, and Refx.

The rack at the studio.. expecting some new toys next week. Retro instruments 176 & a STA-Level, Dramastic Audio Obsidian, Q2 Audio Compex, two API 525’s, two SSL E Dynamics, and two Rupert Neve 543’s.