When it comes to upgrades, apart from seeking out the best possible mastering, it's always loudspeakers for me.
For sure, as I get older/lazier/busier/less obsessed etc I'm looking for an easier life and may want to add streaming/ Bluetooth options but for sonic improvements I don't bother looking past transducers.
If I was to hear a clearly better CD player than my Marantz CD6000ki or a better amplifier than my Creek Destiny, I might reconsider, but as of yet this hasn't happened.
I've done enought chopping and changing of components in my time to finally accept that there's very little of gain to be found down those particular avenues.
Of course things might change, and if some of the things mentioned by Edgar Choueiri in his recent Audioholics interview come to pass then things will be different.
His insistence that the spatial aspect of sound is by far the most important aspect when it comes to realism in audio is one that has made me reconsider my opinions.
I think he's right.