Ruby Amp - wiring 'on' globe changes sound when run from same battery

[wyanganpines]

I've just made a Ruby amp and put it in a fake fender head cabinet. What I want to know is can I run everything from the same battery in parallel? When I hook up the bulb to the battery it changes the sound and stuffs everything up. For the record I am going to add a clean volume boost, matsumin valvecaster and harmonic percolator (the pots are all set up on the faceplate), but I am just trying to get to first base with the ruby amp and the on globe. Any advice? The ruby amp sounds quite good on its own, but the volume needs to be boosted.