Really?  I thought it just listened to the output and calculated a boost as a percentage of the input, i.e. you could be driving cardboard (or flax!) with tubes, for all the DSP algorithm cared.  This is how Dirac Live can work inside a MiniDSP DDRC-24 (e.g.): Dirac knows nothing about the speakers or the amp, only what it hears from its microphone input when it sends out a known signal sweep. And "speaker elements" == "drivers" colloquially so yes, s/he is indeed hooking up the inexpensive Symfonisk amp to the 4000's drivers and bypassing or removing the electronics.  BeoWorld description claims 35 watt x 2 (ICEpower version mk.2), and supposedly the amplifier on the Symfonisk speaker is the TI TPA3116D2, a two channels x 30 watts per -- so it could work OK unless you crank the volume up, maybe? [Edit: the DSP will take some headroom too.] P.S. @carljh, kindly use your first sale to buy a gold membership here, in order to post to sell stuff.

You calibrate the rebuild speaker with Sonos Trueplay which is included in the Sonos app for Iphone and Android. The speaker play a frequency sweep which the phone pick up and adjust the speaker for a flat frequency response.