| Sonic Beat Alliance is an electronic music band most likely consisting of Dylan J. Nathan (The J stands for Jega), and Andy Maddocks of Skam fame.
Not much is known about the band, considering that the only material ever widely released was in the ultra rare MASK series, namely one track on Mask 400 and two on Mask 500.
Considering that Jega has a musical career of his own, and that Andy Maddocks supposedly runs Skam and helps Autechre/Gescom from time to time, the band was most likely an incidental happening for the purpose of the series, and does not exist proper. | 
