I do know that there is no longer any transformer in either the XLR input or output in dart pre version II. and that version II input is much higher performing, as I used it with the Trinity dac and was very impressed.
OTOH while yesterday I did enjoy the absence of noise from the XLR output, later it was clear that for whatever reason the RCA output into the RCA input on the ML3 performed quite a bit better. there are a few variables involved so we are not just hearing these interface issues. the XLR interconnects were generic, the pair less than $50 value, and they were brand new and raw. the RCA's I've had for 5-6 years, are fully broken in as well as recently spent 5 days on my cable cooker, and have a retail value of over $3000. and the noise difference is not hardly noticeable.
the XLR performance seemed blunted and compressed, and had a bit of glare. it sounded one dimensional and lacked bass.
was that mostly the circuit difference? or mostly the cable? or a combination? don't know. I do have a slightly higher level XLR I will try later this week and i'll make sure it's had some cable cooker time.
I do think that in single ended configuration the dart pre seems to be a great pairing with the ML3, magical even. each plays to the other's strengths.