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


I can't believe after all these years, I am asking such a basic "analogue 101" question, but here it goes. I own a VPI turntable that has a "VTA on the fly" knob.  I thought the best VTA setting was for the arm to be 100% parallel to the record surface.  

However, based on some research, I am not so sure that is correct way to set the arm to achieve optimal VTA and correlatively, optimal SRA.  Not sure, ... but I think I have to raise the pivot side of the arm.

Any advice would be appreciated. 

Thanks.     
bifwynne
The big soundstange that LP was recorded on will reveal magic in a system ;-) Tweak a bit then settle in, adjusting it for every LP is a drag….
My cartridge is a Lyra Kleos.  I believe VTF and azimuth are good.  I use a digital scale for the VTF and use both (i) a bubble-level and (ii) a super-light aluminum bar/old fashion ruler to adjust azimuth.  Those settings never change.

So based on the responses above, starting with the arm 100% parallel to the record surface sounds like is a good place to start.  Presumably, the stylus is sitting at a perpendicular angle to the record surface.  I recall reading somewhere that the optimal SRA is 92 degrees.  Two degrees off ... screw it.  Close enough.

Any further comments or suggestions on VTA????  Lewm ... you out there??

P.S. -- I am listening to Linda Ronstadt singing the old classics accompanied by the Nelson Riddle orchestra; the record is part of a 3 record set.  Boy oh boy, ... can LR handle a song.    
VPI owner here.

Don't go beyond  noromance's suggestion. It's just nervosa+  with no music enjoyment.

Find a "middle of the road setting or you can set EVERY LP prior to playing, and feed the disease.
On the Fly is great.

Start parallel as you have, then adjust back of arm up, speck by speck, listening for any preference, particularly high frequencies.

Your cartridge should have specs for it's VTA, look up the related Stylus Rake Angle SRA which is the true goal.

It is more important to get azimuth and VTA correct for advanced stylus shapes. What stylus do you have?
Raised at the back is lighter and brighter. Lower is heavier bass and rolled off highs. Find your preference in between. It can vary by record. Pick best compromise. If it’s off parallel by more than a few degrees to get the sound you prefer, something else might be out of alignment.