Haha yeah those VU meters don't 'dance' like 80's equalizers do. And if they do, you're probably heading towards lifelong tinnitus or serious hearing damage. My speakers are 4 ohms, which might make them move more than 8 ohm speakers on which the meters are calibrated on.
I can appreciate your choice for the 'vintage' Wharfdale Lintons. Estatic wise it definitely makes a difference compared to a pair of (i.e.) high gloss painted B&W's or Elac's. And I think it also gives a certain 'guarantee' of buying a good product, being on the market so long and so popular. But achieving a particular sound that (totally) suits your personal taste is, I think, the most challenging and enjoyable part of this 'Hifi hobby'. Imho, people who talk in terms of a 'better/worse' sound and that something like DAC's or cables make 0,0% difference are lacking the ability to understand and grow in Hifi terms, or are just irrational. Terms like warm/neutral/cold, detail, dynamics, stereo placement, harshness etc. are useful to mention so everyone can decide what probably will be 'better' for them. Thing with DAC's is that the amount of DAC's available, the filter settings plus the importance of the whole (circuit) implementation creates so many variables that it's almost impossible to have a good discussion about it. But I think simple logic says that DAC's (and cables) do matter, sometimes just a bit and sometimes a lot. I believe it mostly depends on the vendor. As in, every DAC vendor has a few engineers that determine how a certain DAC 'should' sound. In my case the ESS ES9018 DAC gives a clean, very detailed but also somewhat flat sound which in combination with my 'vintage' 1993 MB Quart 2000's gives a sound that makes me spend every evening listening for hours without any fatigue (with a little + treble & bass).
In your case I can imagine it's a bit too 'velvet'. As someone who appreciates Yamaha, velvet sound is not something to achieve (too much). Your Linton tweeters stretch to 20Khz, where my titanium tweeters (suppose) to go to 32Khz. From a scientific approach, handy to keep the bats away but far beyond the frequencies we can hear. I think the difference relies on the material (incl. casing) used plus the cross-over(s) settings.So changing to supertweeters can definitely make a difference, but more because of the material used than the frequency range (I think). But I rule nothing out and certainly encourage anyone to experiment with whatever they want.
About your listening space. Personally I have good experience with 'smart' lights (i.e. Philips HUE lights) that can change the amount of temperature. The effects still surprise me every day. I can create light that seems like genuine daylight but also a very warm tinted light that eases and relaxes the mind and is perfect for evening listening.