Thanks very much Todd, for running this program. It was very useful to read all your comments & reviews.
I've just upgraded my UD-501 to the 505, based partly on what I read here (thanks), it arrived today and I'm enjoying it already.
I'm currently running it XLR to my HA-501, driving 150 Ohm HD660S. It sounds wonderful.
But I'm wondering: would it make more sense to sell my HA-501, and just use the amp in the 505, via the balanced 4.4mm jack?
I suspect the HA-501 true Class A may be better, with 1.4W per channel, albeit with only unbalanced 6.3mm jack, but perhaps not much?
I have tried to compare, but don't hear much of any difference. It doesn't help that it takes a while to change the connectors on the HD660S.
Would appreciate any thoughts, thank you.
PS annoyed by the small changes in design from 501 to 505, so now the new DAC doesn't quite match the old HA. e.g. change in wing colour, logo changed from black to transparent embossed, OLED orange to blue, model number location change, control knob size & design, lack of printed volume scale etc. Minor issues, but annoying