Majority D40 Active Bookshelf speakers build quality is good. The bass is well balanced not to case interruption to the sound. I have tested with Bluetooth and AUX. Both works as expected. Please note the AUX input needs to be from a power amp or TV. Please don’t expect to get better sound by connecting your phone to the AUX input. So if you are connecting your phone please use Bluetooth instead of AUX. The other issue is the speakers are not covered. So it’s easy to get damaged. I purchased these speakers as a refurbished for £ 33.95. This is very worth for this price compared to the expensive brands. But I wouldn’t pay its original price £90-120. Overall experience is good , well worth for £33.95.