I was looking for additional notebook speakers that do not need a lot of space, are easy to store, not rely on external power and still perform well. After much back and forth, I'm finally in this speaker "Z305" landed from Logitech. It provides a rich sound that he also brings the other above-mentioned requirements. Simple (and without pressure or scratch points) attached to the notebook monitor, USB plug in and off you go. One can hold no disco with it, but at home for everyday use or barbecue in the garden he has really good sound without annoying background noises and to act without tinny etc. It fits easily in my notebook bag and accompanied me so even when traveling or to the office.
From me, therefore, a strong buy recommendation, if you have not exactly sound for large rooms or arrive to many people.
