High end sound

Sorry about your wife.  

Cables can indeed make a difference, but it involves a lot of trial and error to find what you like. 

Have you considered room treatment? 

Servicing the amps seems prudent too at some point 

There are also some good mods and upgrades available for the crossovers of your Maggies. Some not only improve sound quality, but make them easier to drive. 

Sorry about your loss.

It sounds to me that your main input is turntable?  If so, can you hook up another source, as an experiment?

You most likely have a cell phone. Spotify lets your stream music at CD quality. Getting the spotify signal into your stereo, could be tricky.  You can hook up a PC with the output from a sound card to your stereo. Maybe your PC has a CD drive?

A pawn shop type of outlet lets will sell a Blu Ray player or CD player for less than $100. Blu Ray and DVD players will play CD's. Try one of those as a source, to see if the sound quality changes, for the better?

Just throwing ideas out there.  See if a different source makes a difference. If the sound stays the same, it points towards the amp / speaker combo.

You’re getting the usual go-to solutions - buy more expensive cables, upgrade your gear, yada yada yada.

The truth is, speaker placement and room treatments have far more impact and are more important to sq than upgrading cables or gear. 

Get that sorted first, and it’ll take some effort, before reaching for your purse to buy more gear. 

What type of room treatment do you have?  If you're hearing the same sound multiple times due to reflections that's a problem.  Watched a Darko video a few days ago and he believes that room treatment is the most important thing in your system.  I tend to agree with him.  Until you get that right (which is very difficult) or at least better you're working against yourself with other changes.

by pure elimination it's the amp.