Re: I just ordered a vox valvetronix head...
Which head did you get? The ones with 4 buttons per bank require a Vox footswitch, whether it's the cheap one or expensive one with all the options.
I like the head. I would have loved to have it ever since I started playing, because it's turned out to be the most useful home practice rig ever.
The main thing to know is that the 3 OD models help further shape the sound of the amp. When it's off, the models sound a little dry, but when it's on, you then have OD gain and volume plus amp gain, volume, and master. With all 5 of those knobs, you can pinpoint exact tones a lot better. It even helps to get more punchiness out of the clean amp models.
edit...I just noticed it's the 120VTH on a Splawn 4-12. You're gonna love it, because that head sounds WAY better through a quality 4-12. One of my favorite features is the onboard tuner. Also, the variable wattage and recording outs.