Helix into the Spider Valve 100 Bogner Tube head

[guitargar]

I have a Dream Rig with the Helix Floor, JTV 89f and stereo PowerCab 112+.  It sounds good in my home studio and on stage at church facing back to me.  Unfortunately with the classic rock and pop bands I play in, the sound doesn't translate as well with higher gain patches.  I've spent a lot of time trying to match the tube sound, but still the sound can come off a little plastic and boxy.  I have the head mentioned above that I plug into a Spider 4x12 cab.  The only option I see to plug my Helix into the head is through the power in.  I'm assuming then that I can add different pre-amps on the Helix to accommodate different amp models.  I just don't want to send too much voltage through the Helix to damage the Spider head.  I could try to dial in the modeling in the head, but I've already spent tons of time doing all of that on my Helix.  Just need some advice on the best way to approach this.  By the way, there is no effects loop on my Spider head.  Below was my setup at church until they decided to go totally in-ears with no amps on stage.  Thanks.