So I did some some testing.
Turned the Pre/DAC up to max, had the hiss.
Muted the 4080 inputs, still present.
Muted the 4080 outputs, still present.
Turned off the QSC PLX 1104 amp that drive the AXI 2050's, hiss went away.
So its in the amp, no big deal, even at full volume still have to stick my head into the horn to hear it.
YMMV