Hiss problem. Will an iso fix this?

[jimosity]

I am having some issues with my rack/head setup that are driving me nuts.

I'm using an AxeFX, Egnater M4 and a Bogner Ecstasy Classic head.
I'm using Axess Electronics products to do switching.
<AC-8 for selecting any channel or feature on the Bogner, BS-2 for splitting my signal to feed the Bogner and Egnater preamps, GRX-4 for switching between Bogner and Egnater preamps>

I run my signal like this:
Guitar -> AxeFX
AxeFX Send -> BS2 Input
BS2 Main Out to Bogner Input
BS2 ISO'd Out to Egnater Input
Bogner FX Send to GRX-4 (Loop4) Input
Egnater Out to GRX-4 (Loop4) Return
<<Loop 4 is not internally connected, so it switches from one preamp to the other depending on if the loop is on or not, like a GCX>>
GRX-4 (Loop4) Output to AxeFX Return
AxeFX Output to Bogner FX Return

This allows me to have any combination of AxeFX/Egnater/Bogner preamp tones while using the grid in the AxeFX to assign pre/post fx by placement of the Loop block.

I am using a Ground Control Pro (10 button mode) to select presets.

Now, for the problem I'm running into:
The AxeFX sounds incredible running as a preamp +/- effects into the Bogner
I noticed when I was using either the Egnater or Bogner preamp sections (when the loop was on in the AxeFX), on high gain tones, there was more hiss than should be acceptable. Cleaner tones weren't bad.
I managed to lift the ground connection on the cable running from the Egnater out to the GRX-4 Return and then high gain tones from the Egnater sounded fine with no hiss. That tells me that there's a ground loop SOMEWHERE in my rig that's causing the increased hiss. I tried lifting the ground on the input of the Bogner and that was apparently a needed ground, I tried lifting the ground on the FX Send and FX Returns as well as the cable feeding the GRX4; no go.
It seems that I can't do much of anything to eliminate the hiss on the high gain channel of the Bogner.
Does anyone have any suggestions? It does give a noticeable hiss when I'm just using the head alone and nothing else, but it's at least twice or three times as much hiss when in the rack/head setup I described. Enough to be a problem.
I haven't changed tubes in the head since I've had it (a month or so).
I'm using a monster power strip for powering all units.

Do I need some sort of isolation transformer or something?
HELP! This is such an awesome setup, I am dying to use it live but the hiss is more than I can let slide.

PS: I have a GCX on it's way - if that'd help things at all, that's an option.

 

[muudrock]

I've never encountered hiss as being a ground loop. I could be wrong, but typically ground loops cause hums, buzzes and squeals if their bad enough. I would think that hiss is a symptom of a level mismatch instead.

Dave is the expert on this stuff, but I know when I built my rack using the Mod 50 and M4 and TC effects, I had to spend some time getting the levels correct to avoid extra noise. I do have to use and Iso to break a couple ground loops, but the hiss I had was not a ground loop issue. I don't own an AxeFX but it could be possible the levels in the AxeFX are too low or high. I had this problem on the TC gear which created alot of hiss.

I'll shut up now and let the master reply......

 

[RACKSYSTEMS]

the axe has a lot of hiss using it on the front end. It will react with some amps differently. Now what I would do is put the front end of the axe in a loop so its out of the chain when you are not using it as a effect. You could also use a mxr smart gate pedal after the front end of the axe to kill the hiss. This pedal seems to work well for this. Or you could put it into a loop with the pedal. All of this stuff would be best.