Hi, looking for some advice on upgrading my DAC? I have an existing system consisting of a Musical Fidelity A3 pre and power amp and MF A3.24 DAC (with separate CDT). I have been considering updating the dac and looking at two options: buy a new DAC ( like the reviews of the Arcam M-DAC) or send my existing DAC back to MF for them to upgrade. Would appreciate any advice. Would an MF factory upgrade be better than a more modern DAC? Thanks