Hi Shellac and welcome to the forum!
Normally the Beolink1000 should work with the BC2300 no matter if speakers are connected or not. As you said you bought the BC2300 second hand it might be that the unit was part of a link-system and the option setting hasn't been reset. Maybe the BC2300 is in "option0", in this setting the IR-reciever is deactivated. For stand alone use it should be set to "option 1"
Here is how to set it in option1: When the BC2300 is in stand-by take the BL1000 and press "SOUND" followed by "1" and "STORE". The red Led on the BC2300 should blink once. Now you should be able to control the BC2300 via the Beolink1000.
Another thought: Do you have by any chance a plasma screen in the same room? Plasma screen do emit a "IR-noise" that can cause problems with IR-control.
Keep us informed!
Cheers!
Foxtrott
"The first thing we do, let's kill all the lawyers."
Henry VI, Part 2 William Shakespeare