I'm in the market for a subwoofer and recently read up on ACI's website about the use of high-pass filters to filter out bass signals from reaching the mains. http://www.audioc.com/information/images/hookupd.jpg I can see how this could theoretically clean up the sound of a system by making sure the amp in my A/V receiver doesn't have to devote power to drive low bass signals that will be handled by the subwoofer. But isn't the crossover in my receiver suppose to already accomplish this job? I'd be curious to know if any of you have used high-pass filters in your setup and whether or not it improved the sound of your mains compared to the tried and true LFE input to the sub connection method. http://www.audioc.com/information/images/hookupa.jpg Would something like ACI's high-pass filters help my system at all? If it matters, my setup is a Rotel RSX-1055 driving Ascend Acoustics CBM-170s (+/-2dB at 74Hz). Contemplating adding an Adire Rava (possibly an SE, though I'm not sure what the advantages of the Linkwitz-Riley crossover in the upgraded amp are for my setup... If someone could explain THAT to me, it would be greatly appreciated as well). Thanks in advance!