How Much Power Do Vandersteen 5a's Really Need?

To set the inline filter correctly need to know the CJ input impedence. Most likely in your CJ manual and specifications. IF not you can use Vandertones and a Voltmeter.

After that, you are on to setting the 11 bands of EQ for each channel below 120 HZ.....

I have set 5a up in a 45’ x 20’ x 10’ great room in Charleston, SC....they were flat to twenty in that room.200,wpc Mac amp w ARC pre....Lovely

Credit due Robert Taylor of Taylor house audio for the assist, many on the board will remember him.

Beautifully explained Tomic601

Tomic, thanks very much for taking the time to explain things. It's greatly appreciated. I already have the impedance of my CJ in hand ( Input Impedance 100 kOhms).And I can understand the benefits of the external hi pass filters being employed.

However, I still cannot understand how the internal 5a bass amplifiers get a signal so that they are aware of what to reproduce. The information associated with the music being played is sent from the preamp to the M5HP's, and those then connect directly to the amplifier sending the music signal information to the amplifier, which then provides it to the speakers. Do the speaker connections on the 5a's internally distribute the amplified signal to both the bass amplifiers (for the bass signals), and separately to the midrange and tweeters?  

yes ! The internal amp in the 5a accepts a filtered speaker level input