Experiencing the same issue—here are my variables...
High Noise-Floor / Hissing through all outputs
WHAT I'VE TRIED:
I've tried multiple Line 6 Wireless Units (multiple: G10, G30, & G55)
I've tried multiple instrument cables
I've tried multiple inputs
I've tried all outputs at both Mic & Line levels
I've tried multiple XLRs and 1/4 cables for output
USB connection makes no difference
I've tried tons of amp models (same issue even when clean or in an empty patch)
I've tried multiple HELIX units entirely (both rack and floor models never been used in the same place prior both running on current firmware)
I've updated firmware to latest release on both HELIX models (2.82)
I've tried HELIX native (latest version)
I've tried multiple power cables
I've tried multiple power conditioners
I've tried multiple physical locations: my house, a professional recording studio, multiple music venues including a new music venue constructed for the sole purpose of professional live sound, a newer church building, also constructed with proper grounding and built for live audio. No change.
I've multiple guitars (Ibanez RGA, RGD, and PRS Custom 24: Dimarzio Fusion-Edge and Bareknuckle Aftermath/Cold Sweat & PRS stock pickups). All guitars properly wired. No ground issues. Sound happens regardless of if I'm touching strings or connected metal hardware. Sound happens regardless of guitar volume position.
I've tried running into QSC power amps, multiple DAWs via multiple UAD Apollo Twin interfaces, multiple computers, Electrovoice Live X powered speakers. No change to noise.
There is no difference in the noise when I am physically rotated one way or another in any given room. The entirety of my Ibanez RGD electronics cavity and covers are painted with conductive paint. PRS custom 24s are air-freaking tight stock. This is not an EMI issue with the guitar. Noise persists regardless of if a guitar is even plugged in.
I wanted to troubleshoot the motherfricking heck out of this issue before creating a ticket with Line 6, so I could have relative certainty that I've tried everything I can before complaining. But this persistent noise is beyond me. It is SO loud whenever I'm using a moderate high-gain tone that even with an input gate and noise gate engaged, the noise causes a very audible harshness in my tone and makes HELIX basically unusable for a recording or live setting. I had never experienced this issue in my memory and I can't determine exactly when this issue started, because I had originally attributed it to a simple explanation like 60-cycle hum via EMI or a ground loop.
Please help if you have any further information on what could be happening with HELIX. Thank you!