@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.