I agree with the above posters re: the digital front end, IF you listen a lot to digital sources. No experience on the TT or phono stage (though Black Cube has decent reviews it seems). At under $1k, maybe something like the Rega DAC, a MiniMax DAC? Above $1k, I'd look at Wyred4Sound or Antelope Zodiac.
I also think a sub might help out here if you are listening to music that could benefit from a bit more in the bottom end. Big fan of REL subs. Integrate very nicely with speakers using the speaker level connector.
I would also recommend looking into a power conditioner upgrade. I love my Running Springs Haley, but there are also great products from Shunyata and others. Power conditioners are very system dependent IME, so try a couple out in your system if possible. But most of the big names will be a significant improvement over APC.
So at the low end of what you mentioned, I'd try to upgrade those three things.
At the $5k end of things, I'd start thinking about new speakers or taking a big jump up in terms of your most-used/most-valued source. Maybe a table like a Well Tempered Amadeus (which I own and love) or Simplex? And if vinyl is a priority, check out the Jasmine phono stage. Folks seem to love it. The Dynavector P75 is another phono stage I have liked (for MM and now especially in PE mode with a low impedance LOMC).
I also think a sub might help out here if you are listening to music that could benefit from a bit more in the bottom end. Big fan of REL subs. Integrate very nicely with speakers using the speaker level connector.
I would also recommend looking into a power conditioner upgrade. I love my Running Springs Haley, but there are also great products from Shunyata and others. Power conditioners are very system dependent IME, so try a couple out in your system if possible. But most of the big names will be a significant improvement over APC.
So at the low end of what you mentioned, I'd try to upgrade those three things.
At the $5k end of things, I'd start thinking about new speakers or taking a big jump up in terms of your most-used/most-valued source. Maybe a table like a Well Tempered Amadeus (which I own and love) or Simplex? And if vinyl is a priority, check out the Jasmine phono stage. Folks seem to love it. The Dynavector P75 is another phono stage I have liked (for MM and now especially in PE mode with a low impedance LOMC).