Hi guys this is my first post so hi again. My system is Marantz NA6005 Marantz PM KI Pearl Lite Tannoy DC6 Musical Fidelity xcans Grado 325e AKG k701 . I have started using headphones quite a lot now and am considering a headphone amp upgrade. Looking at Marantz HD Dac 1 or a Graham Slee product would the dac1 be any improvement over the pearl lite headphone stage or the xcans or would the dedicated Graham Slee ultra linear be a better option I love the Marantz smooth sound