I've emailed them before regarding this exact same thing about the gain adjustment. I was told to just provide information like iems used as well as source in the remarks space at the bottom of the order form.
I think they will adjust according though you can probably let them know what you have in mind as well. I personally was thinking of requesting the bass boost to be reduced to just 3db on top of adjusting the gain. They reply emails quite promptly if you want to ask any other questions. You should ask them about the shipping yourself. Hope this helps somewhat.
Hey again Awry,
So Vorzuge and currently out of stock of the Pure, but they do have stock of the Duo.
Did you ever hear a stock Duo amp (for comparison)? When you requested them to reduce the gain, was there any confirmation that they actually did reduce it? Or is the gain OK in your unit?
Since I'll be using the Duo only with IEM, I don't think I would have any use of the treble/bass boost in the stock configuration. I asked them to reduce the gain and to also reduce treble/bass boost but they never actually confirm that they will do it.
Don't wait to have to deal with losing out on shipping both ways if they end up sending me a stock unit.