Which has higher priority, overhang or VTA?

Some good points above, and my experience has been that VTA has a substantial impact on sound.  Conical styli are unaffected by VTA as they have a uniform cross-section from tip to base.  All other styli shapes are affected to greater or lesser degrees.  You should note that 1 or 2mm of VTA adjustment is quite a large change and shouldn't be necessary very often.  Perhaps you are simply becoming more sensitive to what VTA changes can do?

I respectfully disagree that changing VTA axiomatically changes other set-up parameters, however.  VTA adjustment systems move the entire arm assembly relative to the arm board/plinth and are intended to correct for minor differences in pressing thickness.  Provided that overhang, alignment, azimuth and VTF were correctly set for a uniform reference thickness to begin with, they will remain correct when adjusted to a different thickness.  Changes to those parameters can only occur if the thickness adjustment is incorrect for the pressing being played.  

Those changes are indeed audible, and a big reason why I very much prefer arms that have the ability to adjust VTA on the fly.  I believe your JMW can do that and you can hear when the adjustment is just right if so.  It does take repetition and patience to acquire the skill, but oh, so worth it.

There are a large number of threads here with all kinds of information on this point that you may wish to search for more background.  Many posters disagree with my opinions, many agree and many equivocate toward one datum over another.  One of the more entertaining aspects of the vinyl hobby.  The only real rule is:  Do what sounds good to you.

Good luck & happy listening!

Thank you all for your replies. Sometimes, I just wanted to find a scientific explanation on why I hear better with just a micro adjustment on the VTA. It seems many variables involved. I might just hit a sweet spot on overhang, or vta or vtf. And you are right, in the end, what sounds best to my ear are all that counted. 
THANK YOU

dangcaonguyen
Sometimes, I just wanted to find a scientific explanation on why I hear better with just a micro adjustment on the VTA.

Hi Dangcaonguyen
As explained in the ET 2 Tonearm manual by Bruce Thigpen..

Vertical Tracking Angle Adjustment (VTA) - Eminent Technology ET 2 Manual Part. 2

The full manual can be downloaded from here. Go to Support-manuals.

http://www.eminent-tech.com/main.html

Some text from a couple of sections.

From Page 51

Several articles have appeared which address the area of cartridge performance. Vertical Tracking Angle (VTA) and Stylus Rake Angle (SRA). We have designed the Model 2 tonearm to optimize the vertical tracking angle of the cartridge.

The angle that the cutterhead is placed at when a record is cut results in an included angle in the final disc. This included angle must be duplicated with the reproducing stylus or distortion will result. The problem today lies in standardization of the angle by record manufacturers and corresponding standardization by cartridge manufacturers. Presently most records are cut with resulting vertical angles between 16 and 20 degrees. The average vertical angles of cartridges manufactured today is slightly higher than 22 degrees. The result of this mismatch is less than optimum performance for many cartridges.

Although the vertical energy contained in a record represents approximately 40% of the total energy on the record (60% lateral). The distortion levels are dealing with are quite high. In some cases, the vertical performance with certain types of distortion can be improved from 2.5% to 1% or less.
.....in most cases, optimizing the vertical tracking angle will not affect the lateral performance (or frequency response, and tracking abilities) of a cartridge and the result is an overall improvement on cartridge sound and imaging. .......The correct vertical tracking angle is by no means the only way to improve phone cartridges but we believe standardization would represent an important step toward optimizing this medium.

Page 56 - Conclusions

1. Not all cartridges will be improved by using them at some angle other than the intended design angle. (The top of the cartridge parallel to the surface of a record)
   
2. The European record vertical cutting angle standard closely matches the vertical angles present in phono cartridges today. There is a need for a universal record cutting standard which closely matches this.
   
3. If the measuring vertical tracking angle of a cartridge is high (greater than 22 degrees) its vertical performance will probably be improved by tilting it back (2 or 3 degrees) (front goes up) to match present vertical angles on records.
   
4. If the measured vertical tracking angle of a cartridge is 18 to 20 degrees. It will probably perform best when its top is mounted parallel to the surface of the record.
   
5. Some cartridges are very sensitive to small changes in VTA, others are not.

Hope this is helpful
Happy Listening.

Thanks CT,
Calvin

" it seems to me, any time I change the VTA, the overhang is changing also."  Theoretically true.

But hard to see what the issue is here.  You can always reset overhang after adjusting for VTA/SRA.

But you really don't have to.  As a bit of high school trig will reveal, if you begin with a 10" level arm and raise (or lower) it by 2 degrees, you will shorten the overhang by about .006".

Not to worry.