Modding/tweaking my system

Looking at your setup...I would be inclined to address the placement of your speaker system in your room... along with a readjustment of the room layout to be conducive to a proper setup.

You're on the right track with what you're doing but the things you're using are getting all the poor results I would expect. That mat material you're using is more for quieting cars than audio gear. A much better material is TA-102 fO.q tape. This damps micro vibrations revealing inner detail without losing bass or dynamics. Looks expensive but a little goes a long way.

Pull your speakers out into the room. Close to the wall muddles imaging and muddies bass. Worst is the rack by the right speaker, reflections off that are bad. Use a tape measure to align the speakers absolutely equidistant and symmetrical. Then experiment with toe. You will probably want them toed in a lot more for better imaging. But this is a tradeoff, you get better imaging and less room effects being toed in a lot, but also more direct might exacerbate your bright top end. Only you can decide the right balance. 

Get some Nobsound springs and put them under everything. These will clean up a tremendous amount of grunge and smear and get you a more natural sound. Springs are sensitive to loading. By adjusting and listening you will be able to tune your system to a lot better sound. It will take some time to figure out the best combination but it will be well worth it as you will be able to tame that top end without losing anything in the process.

Bear in mind a certain amount of top end glare will always be there simply due to what you are using. But there's an awful lot you can do to ameliorate it without trying to mask it creating problems in other areas like with the mat stuff you tried.

Thanks for the replies guys

The room/life simply won't allow any other positioning.

What you can't see is most of the right side opens into the kitchen over a breakfast bar!

Yes I have to deal with the fridge dishwasher etc.

I've shifted the speakers wider in an attempt to get a wider ss, they've gone backwards and forwards many times over the years. Presently I'm trying the tight right tight back layout seen.

I simply cannot decide the best fit, close as they are seems to allow less toe in helping to open the sound.

Think i may remove the spikes and have a long positioning session, long overdue.

i sit far end of the room behind are patio doors. I have heavy curtains to cut rear reflected sound.

I'm considering an DIY rack with closed off sides and back for transport, dac and pre open back for amps.

The next stage I've been considering is a re-clock, op-amps and some recapping.I want to see how far I can get before open heart surgery.

@millercarbon I'll have a peek at the products mentioned ty

Once everyone has gone to bed I'll play with the sorb balls lol

@millercarbon ty ty ty

Your comment on toe in reminded me of an article where a guy auditioned the FB1s removing a much larger set of PMCs.

The PMC engineer when positioning them had them closer together but with much more toe in than the reference set up.

I've just shifted a bit away from the wall then toed in more than usual and just wow.

Playing my reference back end of the wall I couldn't stop grinning

Things have snapped into position, details never heard before (unless I'm imagining it) bass tighter but remains the same weight. The crashy symbols have shifted backwards allowing more delicate percussion to come to the fore.

Yes its still bright but as you referred to its what I've got.

Rotel kit Fb1s both known as a bright presentation

Now its time to play with those balls

Nobsound springs will allow you to play with loading to tweak the top end down a bit. This will warm up the bass at the same time. Mass loading, adding mass to some of the lighter components like a DAC, is another way of improving bottom end while smoothing out the top. This is all trial and error so can take a fair bit of time and usually no one thing is a silver bullet, but it does add up and you can wind up with a lot better sound in the end.