I was reading the manual for the evo series and it said about mass loading the speakers as this makes a large amount of difference to the bass. So I set out investigating this. I got to the end and pulled out the plug in the bottom of the speaker and found it mass loaded already. I emailed AE and got this reply. Dear Sir, There was a misprint in the manual. The Evo 3 loudspeakers are mass loaded from the factory with the optimum amount of mass loading, there is no need to change this. -- Will Fisher, Customer Support Manager Acoustic Energy Ltd, 16 Bridge Road, Cirencester, Gloucestershire, GL7 1NJ Tel: +44 (0)1285 654432 x235 Fax: +44 (0)1285 654430 Web: www.acoustic-energy.co.uk I hope this helps anyone who was wondering about it.