The sound of Proac Studio 100s is overall outstanding. I love these monitors for mixing because they deliver an accurate sound that covers all the necessary frequencies to do an accurate mix. Unlike a lot of near field studio monitors, these have enough bottom end without being boomy to satisfy just about anyone's mixing needs. They're also great for checking mixing on or for play back during recording, although they sound so good that sometimes they can be a bit misleading if you are just using them to check out some mixes. These monitors would be a perfect set for a studio of any size...
While I've only had a chance to use the Proac Studio 100s a small number of times in a studio that I've done some freelance work at, I've used them enough to know that they deliver a huge sound. The price isn't exactly home studio friendly, but if you're looking to invest in a set of high quality studio monitors, these are definitely a good choice. They have a very realistic sound that won't play you back anything other than what you send to them. For a studio owner of any type, the Proac Studio 100s are a great investment for those looking for a top notch set of studio monitors for any kind of purpose or application.