What equipment upgrades or tweaks will improve the sound of drums?

I would be remiss by not giving a shout out to my New Dark Matter, the quicker picker upper. NDM eliminates both visible red and invisible infrared stray laser light in CD players in less than a picosecond. Restoration of bass frequencies is one of the primary benefits of NDM. I estimate 50% or more of the bass information and dynamics is simply missing in action due to the scattered light problem.

geoff kait
machina dynamica
we do artificial atoms right

:-) All you need is the right powerful speakers, I won’t tell you which, but you can guess!

@in_shore 

Hey in_shore. I just got off the phone with Tony Minasian and he'd like it if you could contact him as he has some music files he'd like to share with you. 

All the best,
Nonoise

I am in Total Agreement with those who have suggested -
AC/POWER.!!

Unless you have addressed your AC/ Power, your system is probably performing at 50% of its potential, if that. I would suggest not to switch out your existing components until you address your Power delivery.

It took me a long time to wrap my mind around it, but once I was exposed to the differences it actually makes - I never turned back. So much more depth in everything, and the level of detail is uncanny.  

One aspect that helped me come to terms with this was for me to conceive my system as a whole investment, and the power delivery as another component - like a amp within my system.  

Look to Power Chords, Cables, Power Distributors, AC Enhancers to invest in.

Good Luck, Have fun

Getting good drum sound goes a long way to getting accurate musical sound, period.  It is in my experience getting an electronic and speaker chain that doesn't distort the harmonic structure of the instruments, including the drums.  After that, it is power.