I would install audio grade fuses and wall outlets if not yet done so.
@davidpritchard gave you good advice, but if it isn't what you want to do, I understand and it's your choice, as is everything in our hobby.
Have you considered trying loaner Cardas Clear Beyond or Clear cables vs your GRs? Might be worth exploring!
I'm not making a statement with respect to the digital front end vs the preamp choice...just that if I were to start the process, I'd begin with upgrading my digital front end, first. And I would explore a number of options (inclusive of the Mytek Brooklyn) that fall within the same budget range.
All the best with your search and choices.
Honestly the difference in preamps would not be better the hovland preamp was a reference grade pre.
The ayre was a good dac but is showing its age.
Also a mac mini or laptop is not designed as a music transport so your path to the dac is compromised.
We would recomend a lumin t2 to replace the dac and Mac mini
Dave and Troy
Audio Doctor NJ Lumin dealers
Speculatively speaking, the answer to your question is the digital front-end, particularly the mac / audirvana, followed by the little Ayre.
Before you change anything, however, I strongly recommend you try a "regenerating /reclocking" device (many of those around, I use this one) —a very good thing to have when you listen to a digital source. Most of them are inexpensive and well worth the outlay. BTW, I'm familiar with your equipment except for the cables; great choices!