I'm posting this to save any others from having to sort this out for themselves. Having been advised by the UK distributor to use Aurora transformers I have discovered that the DA-E60 transformer is not compatible with the 5504D2A series. This is despite Aurora technical support telling me that the capacitance is 10nF (and thus within both the max VA and max capacitance limits of the dimmer) and its supposed compatibility with this type of dimmer. The DA-J60 transformer seems to be fine. Aurora claim that these 2 transformers are identical in specification and weren't able to tell me what the difference is between them. They often supply both the E60 and J60 under the brand "DAIS". The problem I experienced was marked pulsing and flickering. Inexplicably this was worst on the most lightly loaded dimmer channels. I have attached pictures of the 2 types. The DA-E60 seems to be supplied exclusively in a black enclosure. The DA-J60 comes in white or blue. Hope this helps someone else! Phil