I would agree the Hornet is one of the most valuable amps for portable applications, the amp is tiny in size and one of the least obtrusive amps I have ever seen for portable applications.
Its a marvel of an amp in its purpose.
its tiny, built like tank, has gain switches, and has punchy romantic sound for on the go listening.
its the smallest portable amp Ive come across that still looks like its a highly professional product. Its disntinct and unique in its look.
The micro stack is also an excellent contendor in the portable amp market. I also greatly enjoy the sound it provides and once again, the package of this amplifier is also unique and distinct. it not only has gain switches but has "crossfeed!!!!!!!"
, the trade off is battery consumption depending on what module you are using and size.
Ive been eyeing a small portable usb amp for my laptop that is smaller than the microstack, the total bit head might be something you may want to look into also. I have yet to hear one, but this amp is one of my top contendors for portable laptop fi in a market that has very little competition.