I agree with jlingo, the TTVJ Millett is a marvelous little amp, to my taste, the most musical I've heard but it probably doesn't synergize well with all the phones and/or music genre because while some people love this amp, many others dislike it. In my opinion it is not a good "portable" amp, it is more like a transportable. The little tube inside makes noise if you hit the amp on a desk or something hard. Also it makes a tiny bit of background noise with my low Z w5000 so I'm not sure I would use it with IEM.
This said however, to my taste, it is really a super sweet sounding unit, jazz and music that has a lot of prominent voices or string instruments sounds really good through this little amp.