What cause tweeters hiss ?

It seems to me that if the noise goes away when you unplug the DAC, then the problem is in the DAC or its source.
 

@auronthas I’m glad to hear you solved your problem. Getting a better interconnect is up to you. The purpose of spending more money is to get better sound, and to give yourself peace-of-mind that you’re doing everything, within your means, to achieve it. 
 

I would be interested to learn more about the XLR cable you replaced. Have you opened it up to check its connections? One of them could be loose or the victim of a cold solder joint. A poor connection would, I think, add a great deal of capacitance to the line.
Have you checked the cable with an Ohmmeter? I have found pin 3’s (ground) and even pin 1’s (opposing signal) tied to the XLR shell’s tab, sometimes at both ends. Pin 3 (ground) should only be tied to the cable’s shield at one end if it is to perform its proper function. If it tied to ground at both ends it is no longer a shield, but a conductor, connecting one chassis’s ground to another, or even connecting signal ground to chassis ground.
I think I’ve read, on this forum, that the connection should be made at the ‘male end.’ Which begs the question, for me, if it is the XLR connector or the actual pins which are referenced. The male XLR connector houses the female pins; whereas the female XLR connector houses the male pins. The male XLR connector plugs into the ‘source;’ the female XLR connector plugs into the ‘destination.’ Others on the forum have recommended ‘grounding at the preamp,’ which is the destination for an analog source or a DAC; but a source for the amp. Perhaps someone with more insight can clarify matters for us both. 
 

Again, I’m glad you managed to solve your problem. 

@auronthas Interesting article, thank you for posting. I agree with you about the cable, it served a useful life. Not sure what to recommend to replace it, different cables have different sounds and some equipment works better with some than with others. You just have to try different ones and let your ears decide.