I have felt compelled to attempt my first review after recently building Bottleheads premium diy headphone amplifier offering the Bottlehead Mainline. I have built a few of their kits now and the Mainlines abilities have really stood out from other amps I have built or owned in the past.  The design is about a year old but the linage and some of the techniques Bottlehead have developed and used in its topology can be traced back much further and has trickled down from their highly regarded custom headphone and speaker amplifier designs.   There...