Before you change your amp, streamer or DAC e.t.c the limiting factor here, IMO, is the speaker cables and stands. The Tellurium Black are good, I have owned them, but the Ultra Black II will open up the sound of this system a lot compared to the black. Or get Colin Wonfors LS-25 (Colin was the designer of all the Tellurium cables, and the LS-25 is the equivalent of the Ultra Black II, but sold direct at half the price).
Then put the speakers on good stands. The Solidsteel SS-6. You do not know what those ATC monitor speakers are capable of until you do this.
It seems like two quite expensive ancillary items, but you wont regret it and you will stay off the component swap merry go round.