I have had three Beresford dac's and messed around with upgrades to caps and parts. I think that there has been genuine improvements along the way, especially changing to battery power and the firmware upgrade to suit the battery.
It has not been an expensive upgrade path because there is a ready second hand market for all his products. They are just really good value.
It has not been an expensive upgrade path because there is a ready second hand market for all his products. They are just really good value.