I asked, he said he didn't know exactly, it was already modified when he bought it.....He just said he knows the mod is in the gain stage of the amp.

Oh, our engineer was Steve S. Slavich, here's a little about him. Great guy and a great engineer.

(Has worked for Streeterville Studios in Chicago, IL as House Engineer. He has done projects for Sony Records, Alligator Records and TVT Records for such artists as Wyclef Jean and The Fugees, Johnny Winter, Common, Amanda Marshall, No I.D., B.B. King, Koko Taylor and many others.)