I think eventaully after my short list become a long list and then a longer list....I decided to pop to local dealer and actually make some decisions.....I eventually did that, although it was supposed to be a weeks audition, but I like it that much its done and dusted.
I doubt I will use the pre out as I already have Arcam A85 and Arcam P85, so doubt I will benefit. The USB may get used in the future, when I understand all that stuff
Good luck with the Fid Audio too, as that was on my long and extra long list too
So in the end it was worth looking for a headphone amp , but I have had to spend £499 to get the sort of scale of improvement I was looking for. The £100 amp I actually thought sounded worse than my A85 headphone socket.
Looking forward to see if the M1 HPA gets better over the next week or so as that would be a real bonus.
Should I have spent more on my headphones I now wonder