What angle should I set the VTA on my VPI turntable?

@dover , I definitely agree that VTA should not be used as a tone control.
However, I think the rest of your statement may be a bit on the flowery side. Most people, myself included can not hear a degree or two one way or the other and that is probably within the degree of error of the lathes anyway. I am a set it and forget it kind of guy. But when I set it it must be right on the money, as he slams his fist on the desk for effect:-)

One thing a lot of these comments have in common is what I consider extremely large or gross adjustments. This is fine if all you want is to be somewhere in the ball park.   

But for that you don't need a USB microscope, or even a bubble level. All you need is a piece of paper with parallel lines. Hold it on the platter, adjust the arm tube parallel, call it good. None of these other things are gonna get you any better, because from here it must be done by ear.  

Sure you can use those other methods. Just don't kid yourself they are any better. For the simple reason the fine-tuning of VTA is orders of magnitude smaller than anything you can see even with a USB microscope.  

VTA differences I have heard are as small as 1 mark on a VTA dial, like the one on the VPI. On my Graham these were about 1-2mm apart. The Graham VTA adjuster is about 24 threads per inch. It has been a while so I forget but it seems there were something like 30 of these marks all the way around. 30x24=720 so one mark is 1/720th of an inch. Pretty close to one one thousandth. Origin Live thread pitch is finer and looks more like 32tpi. Also the wheel is a lot larger. This probably explains why with Graham I was often times interpolating while with OL the larger marks spaced farther apart were fine. In both cases we wind up somewhere around 1/500th to 1/750th of an inch. 

This is vertical at the pivot point. Do your geometry if you want to work out how many arc seconds that is at the stylus. Go ahead, knock yourself out. As for me I am happy to rest assured it is less than you will ever be able to measure with any USB microscope. You just won't see it. But I sure can hear it.  

Probably a lot think this is crazy. Fine with me. Not the point. I am as always the last one to argue with anyone says they can't hear any difference, don't care, etc.  Just want to be real clear exactly what I am talking about when I say I do.     

If your VTA is off by as little as .01", then however good you think your imaging is, presence, extension, definition and detail, if it is even this much off you can make it better with a few micro VTA adjustments.   

This is why they put those tiny little marks on VTA adjusters. This is what you paid for when you bought that expensive arm. Use it or lose it.

Kleos (and every Lyra I've owned) should start with arm tube level and parallel with record surface with stylus playing.  Then turn the VTA adjustment knob one full turn up and listen.  Then back to level and listen, then one full turn down and listen.  Return to parallel with record surface and listen.  Whatever sounds best, adjust to that position.  Then use that as a starting point to repeat the process.  

At some point, moving the arm pivot up or down one full turn will degrade the balance, timing and imaging.  That means you've gone too far and should start heading in the opposite direction.  

Just as a reminder, tracking force may change slightly with VTA changes.  Check the rest of the alignment during the testing to make sure VTA changes haven't change them.  

remember to use your protractor after raising/lowering the arm....the cartridge will need to be moved forward/backward.

millercarbon, then you need to adjust your VTA with each record as they are all a little different and you think you can hear it. Knock yourself out.