I use xtr400 for 2 years.
The sound of the sub is very soft, very round by the volume of cash and descends very low frequency, however, its size is not an advantage for transport. The sound system is very good quality, no buz, clear sound, in short, the asset has its purest !!! The sound is very linear spectrum has a large share creu to 100Hz.
I tried a lot of time between model and I'm not disappointed in xtr400 moin and yet his rapprot price / quality more than satisfactory.
With experience I will ever be choice for fixed installation but not for displacement because the power / size of the sub is not interressent.
Le13 \ 04 \ 06, I now owns a Sub + RCF speaker system amplified 1600Wrms malgrés and whether the very high end, I continued to advise the XTR400 !!! BTW in a small music room type basement at home, the XTR400 be better suited as powerful speakers and high end. on the other hand in service, there's no pictures Gemini quickly limited.