Neither the Banshee 2 or the Heil Talk Boxes will work without an actual guitar amp head and cabinet. Traditional talk boxes physically go in between your guitar amp speaker output jack (through the talkbox device) and then into the reactive speaker load/cabinet.

Without having one here to test with, I can't guarantee that it will work correctly in your desired scenario. But years ago I remember helping a friend with setting up their Heil Talkbox... the physical routing of signal went: guitar through a few effects pedals and into the front end of the amp. Then, the output of his Marshall head went into the Heil. A tube was connected to the Heil that was mounted on the mic stand. An output cable from the Heil fed the 412 Cabinet.

Check this out for more reference: http://en.wikipedia.org/wiki/Talk_box

I think you might want to give Rocktron and/or Heil a quick call and run the scenario by one of their techs to get the word from them as to whether your setup will work. While our HD500 provides the ability to run your guitar signal through amp modelling (software), our device is not actually a tube amp head and speaker cabinet in terms of physical behavior, so this Banshee won't be interacting with our unit the way I believe that it's supposed to. But a rep from Rocktron can clarify the Banshee's operation behavior do's and don'ts much better than I can. Hope this helps!

Practice with the Banshee using a small full range keyboard amp and a mic.That's what I do when I am home away from my PA gear.I find the  less I process it the better. A little reverb and delay on my vocal mic. live and it's great. People think I'm really doing something when I use it lol  The Rocktron folks should sell PA gear with those things!Good Luck!