Thanks for that link (I should have searched harder). That was very helpful and I think I might try out the D1 first go from there.

I've been doing a lot of reading on various Amps & Amp/Dacs that people have used with the D880/990 250ohm cans.   My main use is listening to music from my macbook air (2012) in my home office. I tried the Fiio E17 through USB but I couldn't tell a difference (My music is mainly 256kbps - so...