audio amplifier for singing arc speaker, 110v design

okay, I'm planning on starting on a plasma speaker, I know somewhat how I want to build it. My neighbor has one of the old school neon sign transformers for sale, he wants next to nothing for it.
So I intend to use that to simplify finding materials. I am incapable of designing a circuit, so I am asking for help. What I need is for somethng to control the 110v for the transformer based on the audio input.
My alternate idea was to use two NSTs and have them become a stereo channel unit. I do prefer that idea myself.
I simply have no idea how to control the sound from the arc without taking the arc out.
Honestly, my electronics knowledge in circuit design made me think a really big relay would work. Until I realized that was stupid.

Anyways, my preferred idea is using a project box to contain a circuit, fused around critical areas to prevent the music device being blown up on accident or anything else bad happening. A stereo plug, with one transformer being the left, the other the right. I also want to try to drive either the low voltage or the 110v computer cooling fan type things so that there is an airflow through the arc. 
Please help me-I can't design circuits for the life of me, and I would rather this work out.
Thanks!