i was in the same situation as u, i have now balanced the sound to my liking with cables. u might get advice from people visiting the forum but hoping for a chance that someone out there has an identical system and not sound bright and respond to this thread is not likely to happen, everything is system and personal taste dependent. However i have spent way too much money experimenting on cables, i've learnt a thing or two about certain brands and their house sound.
So here's a list of cables i think brought warmth to my system, unfortunately i don't live in the UK, there might be brands that you can't buy from where u live, for me i took some risks and bought some from the USA and hong kong a few times.
Siltech:they r really costly if u r into upgrading, i had their entry level(mxt new york for all my components) for awhile, really sweet treble, and mellows out everything, but the bass isn't very powerful, unless get their high-end stuff.
ATL: a german make, pretty full-bodied sound and smooth, good price too, though it makes the sound thicker, some people don;t like this presentation.
Cardas: known for their warm sound, some say their flagship stuff are very neutral but i haven't heard them, i have cardas golden cross interconnect in my system right now, it really has soften the sound.
analysis plus: audition it if u can, it's very clean, which didn't work out for me, i wanted to like it because all my rock and jazz sounded so good, it isn't bright or harsh, bit round sounding almost but a little too weighty, good for bass but too powerful for treble for me.
transparent: another expensive make(mine are entry level bulk cables terminated by this cable dealer near me), are also my current speaker cables, it has really sweet sound, no emphasis on any audio band, the most coherent sound i've heard on my system so far, the bass is truly defined, really warm midrange, and this completely tames my treble without sacrificing anything. I'm definitely keeping them.
Audience: they sound so organic, but i feel one could only achieve the full potential when using them with every component.
PS Audio: i find the tonality is on the warm and dark side, though everyone's raving about their power conditioner, and kind of forgetting that they make pretty good cables as well.
good luck