Rodman
Nice article... a bit dated but good thoughts there.
Syd
My exp has been such that once a prime digital source has been selected. One capable of conveying all the info it gets from the presented media, changes to the down stream items & accessories yields still more benefits.
The media too, as was noted can effectively lift system performance, albeit not nearly so much... but still some.
given your desire to not pursue wholesale chages, and the items you now own aren't bad ones, nice in fact, I'd consider moves surrounding the source, and the way it delivers it's info to the preamp, first.
Every system I've had which used a preamp, the preamp can be (and IMO), is as important as the source. In other words I put as much $$$ or more into the preamp as I do the source... routinely.
owning a lesser Odyseey amp, it does respond well to isolation, and power cable changes. So there's that.
The bottom line for me as of late has been this... "If you like what you are getting, keep doing what you are doing. If not, change what you can, when you can. Everything makes a diff in a good audio system."
AS was noted too, other musical content/genre than rock & pop will reveal more overall sonic qualities.
Using the best recorded media seems to me the best way to establish and monitor changes in performance as ones sytem develops... whether I like the genre or not to begin with. Actually this path also unlocked for me new doors to audio and has since allowed me personal growth in music appreciation. My horizons have been broadened, let's say.
In fact, due to the quality of the recordings in some of these other musical areas, I now prefer them to my staples of blues & alternative music. Sheesh, I'm even digging big band jazz lately! hampton, Miller, Pepper, Goodwin, Jacquette, Nocturne, and others. Dare I say it? yeah, classical too just recently.
Again, "If ya like what you're getting...."