New system too bright.Will different cables help ?

That's why tone controls were invented.

Is it with all music or just some?

As Tvad suggests, you may find there is nothing you can do to compensate for the component that is causing the brightness. That would be a good place to start.

Having said that, I once owned a Bryston / Thiel combination and loved it except for the brightness. Once I switched my speaker cables to MIT, everything came together. If it's easier to switch out cables than to replace the source of the brightness (or if you like everything about the source except for that), try some MIT's to see if they make a difference -- you can normally try before you buy so there should be no risk if you find the right dealer. I've had excellent luck with Joe Abrams, but don't forget your local dealers.

What??? You sold your NAD's???? J/K. I agree with Tvad, can you remember when the system started sounding disagreeable. It's hard to nail down the real culprit when there have been so many wholesale changes at one time. I also don't think that cables can make that big of a difference, they are more of a tweak, then for fixing big problems. That being said, I'm only familiar with your cables, I haven't had the opportunity to listen to any of your components/speakers. In my experiences, DH Lab cables tend to be forward and unforgiving, they can sound bright in some systems. I can also say that I agree with Ozfly. I'm not a fan of MIT cables, but they sound their best in bright systems. If you cannot trace the brightness to a particular component, maybe trying some MIT/Cardas/Transparent cable instead of your DH Labs may help. I may make it listenable, but probably won't make it warm and lush.

Regards,
John

You may be confusing brightness with sibilance. They can sound very similar. Cables with good metallurgy eliminate this sibilance without losing any detail.