James LaBrie (Dream Theater), Anneke van Giersbergen (ex-The Gathering), Eric Clayton (Saviour Machine), Magnus Ekwall (ex-The Quill), Marcela Bovio (Stream of Passion), Johan van Stratum (Stream of Passion) et Ed Warby (Hail of Bullets) y ont notamment participé.
Ayreon
Dream Theater
The Quill