I have finally opted for the DCS Combo (Purcell+ELGAR). The results are outstanding and far outperformed the DAC64. I did not have the chance to listen to the Blu, but I am very happy with my Mephisto + DCS combo. Note that the digital cables play a critical role in this setup. I finally chose Tara Labs the One: perfect neutrality and all the details without an inch of agressivity. Thank you all for the input.