I just had a chance to listen to the GoVibe Porta Tube at Jaben in Hong Kong and I was deeply surprised by its sound. I paired it with my own travel companions my iPhone 4 with ALAC and DT-1350 and a pair of HD650 present in the showroom and specially with the DT-1350 it was a great combination. I only had 15-20 minutes in the shop as I was on my way to the airport but that was enough to put this amplifier on my list. This amplifier is the most rich and lifelike portable amplifier I have heard with great detail and a warm-ish sound to it.
I could not find a lot of info about it here. That is probably because it was released for sale less than two weeks ago but if anyone has done some comparisons to other portable amplifiers I would love to read more about this. It is not the smallest portable amp but fully worth the extra size.
Here are some pictures.