The pre di , is before everything, so the signal sent to and from the di , will be totally unadulterated. The post di will have a little magic on it, even if eq is all flat.
I have a TT800, and run both channels basically flat, all my eq is done before the amp. The post di , obviously picks up the gain settings, and the 2 voices of my amp. The magic (cab sim, valve emulation), is subtle, but definatly there.
IMHO, the di's on these heads are way better quality than any inbuilt amp di , iv ever used. On par with many top end , stand alone di's.
I have a TT800, and run both channels basically flat, all my eq is done before the amp. The post di , obviously picks up the gain settings, and the 2 voices of my amp. The magic (cab sim, valve emulation), is subtle, but definatly there.
IMHO, the di's on these heads are way better quality than any inbuilt amp di , iv ever used. On par with many top end , stand alone di's.