VPI HW-19 with Graham 1.5 arm Question/Suggestions

Try a thin platter mat. Home made from leather or cork as an experiment. Also try it without the clamps and stuff.

I like all these suggestions, especially the easy and inexpensive ones. Thanks!

My preamp is a Jeff Rowland Consonance with onboard phono module. It has dip switches inside to change the cartridge loading. I could play with those.
VTA is easily adjusted (on the fly) with the Graham 1.5. I could play with that.

My amp is a Cary CAD-280SA V12.

I was considering a ProJect Cork-It mat. It is only 1.5 mm thick. I could easily try it without the VPI clamp.

What about footers?

Presently the table has four cones underneath.

I was considering the IsoAcoustics Gaia III footers.  
Has anyone tried these under a turntable?

Do you know how they might change the sound?

Throw away that mc cartridge and get a Stanton 881S with original Stereohedron stylus.

It is very hard to predict what a set of compliant footers will do, particularly when the table itself has a suspension.  Now you have two sets of devices with their own resonant frequencies and behavior.  I doubt that footers will be a big help for the tonal characteristics you are describing.   If the table/arm are contributing to the sound you are describing (sounds like too much damping is what you might be hearing), then perhaps a different platter mat that provides less damping will help.  You can do that for free by removing the rubber ring around the spindle of the VPI which is part of the reflex clamping system; with the ring removed, a record will lie flat on the platter and you can then dispense with using the clamp.  With the record less well coupled to the platter, it will ring a little bit more (vibrations imparted into the record by the stylus playing the groove will not be as well damped) and this might change the sound in your favor.

It has been a long while since I had your arm, so I don't quite remember if the instructions talk about changing the amount of silicone damping fluid in the uni-pivot housing; you should check if that is another way to tune the sound to your liking.  

The far more costly alternative involves getting a new cartridge.  There are models that sound warmer than others by a considerable degree.  For example, most Grado cartridges are one the warmer side, with a prominent upper bass/lower midrange and slightly boomy (less tight) bass.  I find Grado's too be too murky sounding for my taste, but, taste vary.  Many of the Ortofon models below their very top models are also on the warmer side (except the "Black" models of each line that use a Shibata stylus) and are not as murky as the Grado's.  The real champions of the warmer sound are Koetsu's, but, most of their cartridges are quite expensive.  Koetsu's are rich, warm and relaxed sounding while still sounding clear and dynamic--this is a very hard mix to achieve.