Hi,
I'm no technical expert but I had a beosystem 2500 for years which I used with a pair of Beolab 6000's - having ditched the beolab 2500's.
I had my 2500 unit plugged directly into the mains - with each speaker plugged in separately (3 plugs in all) with no problem at all. In fact I believe that each having their own direct mains supply is the best way anyway rather than feeding through something else (i.e. speakers)
So definately yes, plug in ur 2500 unit and your 4500's with their own plugs and you'll be fine.
Regards
Michael
BV5, BV Avant, MX4000, MX1500
BS 7000, BS 5500
Penta III, Penta II, BL 4000, RL 60.2, RL 35, CX-100 Alu
BL 7000, MCP6500, MCP5500, BL 5000, Beo4 (x2), BL 1000 (x2)