I agree with this, John.  Fuses and grounding boxes won't fix a poor system, but they certainly enhance a well sorted system.

Read in another place that fuses and mains cables were tried but made the system sound worse

Highlighting a not so well sorted system .....

I think a time for reflection with all the changes I made this year.
My amplifiers and bass drivers being the only gear that has not changed.

Speakers
I started off the year with the Faitals. They could shift air for sure and at the weekends could sound involving. My only issue was they break up if played above 93 to 95db. My first  change was to the Kefs centre speakers. They do depth and detail really well. The Temples had no issues driving them. After visiting Vic again I moved to the Klipsch I love the low mid bass push they have that allows the system to really rock. They are open and effortless in sense of scale when matched with my bass drivers. I enjoy the presentation and they just makes music fun.

Digital
I started with the Tinkerboard, them the Limetree and then Bluetooth. I also had a upgraded Mutec and the Topping D70 DAC along with some highly tricked Linear Power supplies. I had cables running everywhere and sure this had a negative effect on sound quality. The first move was to move to Bluetooth I know the Limetree better but getting the best out of it would mean audiophile hubs etc and by this point I wanted to simplify my system. I just got tired of all the cables and gear I had and still would need to invest and buy more gear. Another visit to Vic and hearing the SMSL M400 convinced me to try this. I managed to get a good deal on the A22 and sold the Mutec without listening to what it does in the new system. This meant I could move the router into another room and get rid of the LPS

Mains issues Frustrations Grounding and fuses
At this point I had one outstanding issue to solve. Grounding all my mains really helped clean up the system. It also added depth detail and fluidity. Replacing internal and external fuse took things up even further. Not sure if I should do the Temples as really enjoying the sound but guess good to get on sale or return.

Support
A new wooden rack and BR big pads to the Temples and Gustard
Mad Audio Science XLR cables from Gustard to Temples

I guess the main thing I do not have the issues with sound anymore. This is a relief more than anything else. System is now as simple as it has been since I had the MF Nuvista 3d cd player but the sound is at a level that just effortless, fun and musical.

In my experience (which isn't massive) slow bass is a product of designs that rely on the back wave ie ports and passive radiators  Even though they might not go quite as low give me a sealed bass speaker every time (or open baffle).

Timing is everything.

So a quick bass driver journey in the last ten years
Wharfedale Opus 3 ported Needed to have a powerful amplifier with lots of grip would go down low but no texture
Open Baffle
Hawthorne auggies Nice texture but lacked a bit of bass speed
Neo Selenium Open baffle more texture and speed but not extending low
Isobaric in open baffle More texture and speed
Baffleless even more texture and speed
Using Klipsch meant lowering cross over bass drivers not as strained so going lower

Aha !

It's not bad, but I don't use the Qobuz interface. I use BubbleUPnP, which has a nice interface including the metadata from Qobuz.

Over the last few days, I have been playing with different music providers,
With Bluetooth, I hear the limits of the technology in that apart from level matching, it is hard to tell them apart
This doesn't mean I would go back to using a streamer. I think you have to pay so much attention to everything to get to where I would want to. I do not want to go down this road again.
It's not that bad. It's beating my old Limetree, and ATB neither are shabby, and I love the simplicity of the approach.
I know I could have taken the Limetree further with a similar route to Martin, but I do not have the space. .
Watching Jeff Beck perform on YouTube right now and pretty happy hearing his excellent phrasing and use of volume

I met Vic on Friday we both did LF Tests before we met.
Vic helped me finish the grounding box. We tried it his system. His system to be honest just sounded right. Open dynamic without a hint of harshness. Mine in comparison has a touch of harshness in the treble, but also a bit more impact on the mid bass punch. We have a similar system. However Vic leaves near a small sub supply and is probably the first house on the supply I have no idea where my house lies and I am near a factory.
We were speculating on my issue I have a smaller room so perhaps room issue.(Getting difference reference points is good as allow you to be better understand, what is going on)
The grounding box hardly made any difference I was pretty sure I heard a difference in volume and Vic was not paying attention so did not hear anything. I agreed what ever difference I heard was minimal.
Going back home I connected the earth to the Furutech Mains supply I have. Initially sound was unbalanced as bass improved first. I have the Behringer and Gustard running from this supply.
After 30 mins it started to gel and within a hour my system on par with Vic apart from mine has more attack and his has a bit more space I think that suits are preferred listening choices well.
My biggest take away is the lengths I have to go too to get to a similar playing field as my friend.