Bought one of these recently. I know these cheap tube preamps don't sound as coloured as more expensive valve amps but I'm starting to think the tube doesnt even do anything at all.

I recorded 3 takes of uh...vocal stuff. 1 using the preamp with the tubedrive set to 0, one with the drive maxed out and one tht bypassed the preamp completely straight into my audio interface. There was no audible difference between these takes, not even an audible difference in hiss levels.

I've read tht they have an led behind the tube to make it look like its active and that's certainly what i thought it looked like first time i turned the thing on.

So i guessing the whole tube part is just bullshit. Anyone have any experience with these?

I'd say you've got that a little backwards. The basic purpose of a preamplifier is to amplify the mic signal to line level. A well designed preamp (either tube or solid-state) should be able to do this while adding very little 'colour' to the sound. All the hype about tubes adding warmth or whatever is mostly a marketing gimmick. It sounds like you want a tube distortion, not a preamp. There are certainly some sonic characteristics that differentiate tube/solid-state and transformer/transformerless mic preamps, etc. but these are probably more subtle than you would expect.

There have been some discussions about the tube pre before so check the search.

One of the things mentioned was that when I look at files that go through it in my daw it does not have any sound below the 0 point on the wave meaning one side of the wave form is missing. Someone else mentioned it and I have notice it too.

The tube that comes with it can be repaced with a ei 12ax7 and it will sound less distorted. If you turn up the tube part you should hear some hiss and some edge or harmonic distortion added to the sound. I find that unless I want to trash something that the tube replacement and using the tube aspect in small amounts is fine for me.

I find it useful but other folks don't like it. It may not be for you if not return it to the store.

Any starved plate tube pre's (like the ART ones, and probably this as well but I'm not sure) are basically bullshit. If I recall correctly this one is "Hybrid tube" and all of the actual amplification is done by the opamps. The tube is there to bump the cost up a bit and fool people into thinking its a tube pre.