Hi,
Yes, this is possible! Please use this cable to add the Core to the Tape input of the Beomaster 3000:-
Although your Beomaster 3000 receiver doesn’t have Powerlink sockets fitted, you can still connect the Beolab 6000 speakers by one of the two methods below:-
1) Connect two speakers to the headphone socket of the receiver with this cable: https://soundsheavenly.com/line-in-connection/77-241-minijack-to-beolab-line-in-using-phono-rca-sockets-one-cable-for-two-speakers.html#/2-length-1m
2) Connect two speakers to the speaker terminals on the back of the receiver using this special Attenuated Converter: https://soundsheavenly.com/line-in-connection/33-power-amplifier-to-beolab-line-in-attenuated-convertor-kit.html and then use this cable to connect the speakers to the output sockets of the Converter: https://soundsheavenly.com/line-in-connection/6-30-av-processor-pre-amp-sonos-to-beolab-rca-line-in-one-cable-for-two-speakers.html#/2-length-1m and you also need one set of these DIN plugs: https://soundsheavenly.com/beovox-passive-unpowered-loudspeakers/74-2-pin-din-plugs-sold-as-a-pair.html
Option 1 is cheaper, but the cable will be visible at the front of the receiver and this will disable any other speakers connected to the receiver. Option 2 allows the cables to be hidden and the Beolab speakers can be used along with your other speakers if required.
Please set both speakers to “Line” mode using the small switch near the input sockets.
Hope this helps! (Sorry for replying in English!)
Kind regards, Steve.