Greg Christian

Greg used this amp head during the time he joined back Testament. At 0:32 you can see the head(s) on the Ampeg 8x10 cabs. Greg used this head as his main amp head for many years later on. You can even see the same head on a video called “Testament - Gear Tour 2012” where Eric and Alex discuss about their rig they used for during Dark Roots of Earth. At 4:40 you can see the Ampeg SVT 5 Pro in a rack on the top of the Ampeg fridge, mostly like Greg’s rig. Even when he left Testament you can see pictures of him preforming with Trinity Fallen and many other bands with the same Ampeg head in his rig.

Greg use these cabinets during the time he joined back Testament. You can see the Ampeg cabinets on the back along side with Alex's and Eric's cabinets during the performance

Greg used SWR bass amplifiers in 1992 but he might’ve used them earlier, not really sure but this is the first sighting of seeing his bass amps on stage. At 2:40 you can see one and later on another one on the other side SWR Goliath II 4x10 cab, just right under Louie’s drum-set

Greg Christian reportedly used the SWR SM-400 bass amplifier head, as mentioned by user 4stringmf on Talkbass. In a discussion about Greg's tone from the late '80s, 4stringmf shared that they purchased the SWR SM-400 head because Greg used it with his SWR amps. This insight comes from a community thread focused on Greg Christian's sound during that era.