Berkeley Alpha DAC 2 - Filter & Volume Setting

2 questions for BAD2 owners:

1) Which filter setting is best to use? Is the filter selection "set and forget" or do you need to change the filter for high res vs. standard res files?

2) Which volume setting do you use when outputting to a pre-amp? The manual recommends 55 - why this setting vs. the maximum volume setting of 60?
By leaving it 55, if you play an HDCD, you will have about 6 Db of more headroom for improved dynamics. This is what BAD told me when I asked the same question.
Interesting, thanks Bugman03!

Berkeley actually got back to me today and this was their response:

The optimum and default filter type is 1 in all cases. The other filters are for professional test purposes to hear what recordings will sound like on more typical players.

Concerning the optimum volume setting, it will indeed vary from system to system and you should simply use what sounds best in your system.