Hello all ! As i plan to buy the Hifiman HE 400 in a few days and possibly one of the 3 others later, i'd like to invest in a desktop AMP (that also can be used as a pre-amp and be plugged USB on my mac) that could drive all of these headphones, but a very good one for Maximum 400$ (i know it's not much to have a very good amp...). So what tube amp (i love tubes) would you recommend me that is allround for these headphones and would drive them perfectly for this budget ? I first thought about the Little Dot MKIII or MKIVSE, but they are quit not recent (year 2007-2008) and i'm thinking that a more recent one would be better ? Anyway, if for the same price i can get a non tube amp that is better sounding, i can forget about the tubes... Thanks a lot.