I have the same amp and Helix!! 1> Make sure your using the 4 cable method, from Helix to amp!! Dont use any amps at all from the out of Helix to the input of the amp. 2. Jvm cant handle any amp in the effects loop!!
Check out Line 6 Power cab +!! You can set up the sounds you want at home, and take the Power cab + and Helix with you. Set it up and Bingo your all set up!!
Yes the Helix sounds fantastic with no cab. So lets think a second. If im using a guitar cab from my Helix, i dont really need a cab or ir in the Helix. I run my Helix straight into my P.a!!