Please evaluate my system...

I not only have direct experience, I have owned a VTPH-1mc and upgraded to the VTPH-2 and then had that unit upgraded to a VTPH-2a.  I also own a VTSP-3a R03 preamp.  I am a Herron Audio fan because of their products' performance.  I have also owned Mark Levinson and Audio Research electronics, but ditched them for Herron electronics.  I have heard nothing better.  

One of the biggest upgrades I’ve made was the Soundsmith Zephyr MIMC. 

HRS isolation base

anytime I hear ditch or smoked, I run....

Vibration mitigation!  Doesn't have to be big ticket.  Contact the Herbelins at Herbie's Audio Lab.  Tell them about your system, the type of sonics you prefer and they will do their best to get you there with their high value products.  Please note:  I have had the pleasure of corresponding with them on occasions throughout my audio journey and they have never steered me wrong or to the most costly solution.  

Consider upgrading your interconnects and speaker cables unless you are already in good shape there.  

Treat your room but don't overdo it there.  I found that the better my system the more I was removing from the room as I originally overdid it.

Good luck.  It's a journey worth taking!

Tim; You have a fine system. It is always easy to recommend changes to every component of every system. After all there is something better just around the corner. The real question is how to make changes and then be sure that what you hear is indeed an improvement. This is only possible if you change one item at a time so A/B comparison is possible. Whilst the DL103 is a fine cartridge and its performing way over its price/performance expectation I believe you may get get a lot more out of your records by switching to something like Lyra Delos. Your VPI is perfectly capable of handling the Delos and so is the Linn Phono stage. Good luck in your quest.