Here I am 8+ years later and ran into the problem described here, I thought I was crazy...
I finally started playing regularly again about a year ago (after about a 15 year hiatus), and loving my Variax 700 as always. Bought a Helix to go with it, still turns heads all the time. (My poor Vetta II is now just sitting around for when I need to connect the Variax to Workbench.)
Eventually I wanted my custom tunings to be based on the Les Paul model instead of the Strat model, and managed to get a Parallels Windows 7 machine set up with Java 6 and Workbench 1.75. Things seemed fine, but...
All my custom tunings had this weird hiss. Unlike all of the various folks guessing and troubleshooting from afar on the internet, this was not the notes from the physical strings in the air, and unrelated to magnetic pickups or resonance, as it happens with straight headphones. And it didn't happen until I edited patches with Workbench 1.75.
Luckily I had backed up all my original Variax bundles before I started editing. I reloaded all of that, and with the original patches (edited with who knows what version of Workbench, probably back in 2005), no funky hiss. I still want to sort out an older version of Workbench, because I am convinced if I can go back in time far enough, I can get the tunings I want with the guitar model I want and without the hiss. In the meantime, the patches I edited in 2005 will just have to do.
To be more clear - you can load old Variax patches with 1.75 and you won't have the hiss. Edit those patches with 1.75, and you get hiss. I have not messed around with any firmware and do not intend do risk that for 20-year-old out of support product.
Meanwhile, does anyone have a Workbench 1.5x installer they can link? I'll ask support for it, but I don't have much hope in help there.
