New system too bright.Will different cables help ?

I recently sold my 10 year old NAD system and upgraded to: Myryad Z140 integrated amp, CEC 3300 CD player, Castle Richmond bookshelf speakers, DH Labs T14/BL1 cables.
I liked the Castle speakers in combination with the NAD stuff, but now the sound is overly bright, I miss musical warmth. The NAD 502 CDP (1bit) connected to the Myryad amp sounded great. After selling it I first tried the Myryad Z110 CD player (matches the Z140), which sounded extremely harsh too me, even after some burn-in time. I returned it and then got the CEC, which in comparison sounded ok.
The resolution and detail of this system is certainly much better.
... But the sweetness and musicality is gone.
My question: Will different interconnects, dedicated power cables/conditioning do the trick, or do I need bigger speakers/subwoofer, tubes, external DAC or even a different amp ?
Ask yourself when the brightness appeared, and perhaps you can narrow down the problem. Other A'goners have cautioned against using cables as tone controls to "fix" (mask) problems inherent in equipment, and I agree. You could spend many hours and dollars in a search for the Cable Grail, when a component swap is in order. From your post, it reads as though you did not detect brightness with your Myryad amp/NAD/Castle combination? Once you put the CEC player in the picture the brightness appeared. Perhaps a different source would bring the musicality back.
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.

You may be confusing brightness with sibilance. They can sound very similar. Cables with good metallurgy eliminate this sibilance without losing any detail.
If you're going to try cables, be sure to consider Cardas, as they are known to be warm sounding with losing detail.
Start with the DH Lab cables, if they are the silver plated copper ones they can sound bright. If that dosent do it, find someone who will help by switching some of their stuff in and out untill you track down the culprit. Some combinations just dont gel, so it dosent necesarrily mean you have any one component thats 'bad'. Take some time and narrow it down.
In your case, I feel switching out the DH Labs for something like Acoustic Zen will make a significant improvement. I used Silversonic T14 for some time and felt it was quite lean and revealed the nasties present in my various systems. The AZ line of cables are extended and smooth. Even the Silver Ref II is a smooth sounding cable. You might give the AZ WOW a try.

I own a few different NAD pieces, the 502 being among them, and I feel they tend towards being musical, not bright. I've never heard or owned any Myryad gear, but it could be they are more revealing than the NAD components they replaced and combined with the DH Labs cabling could be the cause of the increased brightness.
It's easy to see from the various opinions regarding cables how one can
get hopelessly caught in an experimental tangle of interconnects.
Everyone who has posted has good experience with the recommended
cables in their own systems, yet few can agree on the best cable
solution, and none have experience with the mix of components that
"Khm74" has. I maintain the best solution is a careful and methodical
component swap starting with the source or amp while utilizing a good,
inexpensive, neutral cable such as Signal Cable Analog Two.
I agree with Ozfly.MIT tamed the forward upper treble on my Thiels.
The Thiels now sound super!

Dont get suckered into buying a new amp/speakers etc..many say cables are a bandaid.
I say, if they work thats all that matters.
Cables can make or break you, but you need to remember that NAD stuff tends to sound overly warm and smooth in exchange for details. I am a strong advocate of proper power delivery/noise control measures and will strongly suggest you start there. The more revealling a system the more harsh noise (glare) will sound. If you start at the source you'll be able to tell if this is the right direction and then work your way down the signal path. Since digital equipment consumes so little power you can do this rather inexpensively. Get a little 2-3 ampere ONEAC isolation transformer from eBay ($15-25), clean all the contacts inside & outside w/ DeOxy and treat them w/ ProGold. Use that on your CDP and listen. If HF glare goes down then keep working on the upstream side of your player until you can improve no more. Then move down the signal path. I would get a Porter Port cryo'ed outlet and a decent DIY based design power cord for the CDP(Bob Crump, Chris VenHaus). I have a CEC built belt drive transport and it reacts very favorably to power cord upgrades. The same goes for my little sister's NAD receiver. I had a surplus military grade, silver plated copper, Teflon power cord hardwired to it and the improvement was stunning. Bass improved tremendously and the vocals became smooth and airy.

Here's the testimonial of someone who followed my suggestions:

Power conditioning and cryo treating

I have tried DH Labs Silver Sonic interconnects and they just didn't make the cut in my system. Perhaps some solid core copper like the Straightwire Rhapsody II's or Tice PC3 will be what you want. Don't forget to allow your system at least 100 hrs for break-in.

With psychic power and primal intensity,
Thank you all. I think I am gonna start with replacing the power cables/wall outlet (thanks psychicanimal). It makes sense to me to start from the source of the signal. It will be interesting to see how much the sound of music can be shaped by minor changes like that. I'll keep you informed.
I just got the Blue Circle BC-86 MKIII (Noisehound). It made a subtle difference. The extreme brightness (digital glare) is gone, and also bass performance has improved. It didn't solve everything, but it helped.
After connecting the CD player to a simple ONEAC transformer, the sound improved a lot, less glare, more bass foundation. Great device, and the most inexpensive addition to my system. Power chords helped too, but the biggest improvement was the ONEAC. Thanks for the advice.