The Perfect Declipper from Thimeo improves the quality of maxed out and overloaded recordings, including modern and contemporary recordings, by calculating missing or clipped sound information from audio data that's still available. It is native to Thimeo products, as well as Omnia and Aqua Broadcast software, among others.
Most declippers restore spikes based on the last few samples just before clipped audio starts, and the first few samples after it ends. While this restores some lost dynamics, it often doesn't remove the pesky distortion that's usually the byproduct of clipping.
Perfect DeClipper uses an algorithm to restore clipped areas in audio recordings by not only restoring the dynamics, but removing almost all distortion.