@vrikkian room treatment and the addition of a sub are 1a and 1b. You can experiment with room treatment with pillow’s, throw rugs, blankets and other various items. Google / hit up some forums with threads, it will give you some solid, creative ideas that you and your better half can likely both live with. On a sub, I’d reach out to 2-3 different manufactures, distributors for advice. SVS, Crutchfeild, The Music Room, Upscale Audio. Ask for their advice based on your placement, space limitations. If there isn’t a solid solution found for a sub then look to sell the Focal’s and focus on bookshelf speakers known to put out solid low end performance through clever design and engineering. Buy used, you might be able to stay on budget with the sale of your Focal’s. Alta Audio Alyssa’s are an example of bookshelf speakers that can really fill a room, have a surprising low end performance. There are other brands, models that can do the same.
If you then get pulled down the rabbit hole of upgrades, I would focus on your amp first. You can use the Cambridge as a streamer, DAC, Pre and feed a standalone Amp that if you upgrade your speakers, would be the next best step. It would maintain the ease of use of your current system, outside room treatment would check the biggest influencers on performance, speakers and how you feed them.
DSP / Room correction was also recommended, you could look at something like the Wiim with DSP / Room correction, inexpensive little unit that can stream, has a DAC and most importantly has DSP / Room Correction, really cheap entry into exploring if that makes a big impact and could help you figure out how to room treat which is an overall better option than DSP. I’m not sure if your Cambridge is a Roon endpoint, you can also do some DSP using Roon, you cloud research that and trial it for free. That would take more work and either your ability to figure out how to adjust the frequency responses to offset shortfalls of your room or having a 3rd party design some filters for you.
As your system sits right now it appears to be well matched, balanced. I can’t speak to the synergy which is key but on paper, you have done a nice job matching components that should compliment each other. Strongest portion of your system seems to be your vinyl set up, that’s probably the last portion I would look at. Tempting to tweak the set up but you likely need to upgrade other components first to really appreciate the incremental improvements you’ll get from the incremental changes, improvements to your TT, vinyl set up.