Vox AC30 head
Matt Bellamy's favorite recording amps are the vintage Vox AC30s from 1964 and 1970. The '64 in particular because of the extreme spike of its Top Boost.
Before he used Kempers, instead of using the older 'fragile and too high maintenance' vintage AC30s on tour, Bellamy switched them out for an AC30 head (allthough in the very early days during some performances, he used a Vox combo amp as seen here)
Bellamy uses the AC30 for his core sound and then mixes in his other amps. Matt said the AC30 provides the attack and the clarity, while the other amps provide the saturation and the sustain.