I now connect Audioengine A2 speakers to my MBP using the single pin TRS audio output. Alternatively this system also works when the output from an Airport Express is connected to the A2 speakers . When I bought a pair of Dynaudio BM5A active speakers, the manufacturer said that I have to use a "bump box" to raise the level and impedance to connect the speakers to the MBP. I am trying to avoid a rat's nest of wiring. Will the BM5A speakers not work if connected without a bump box or will the sound be of inferior fidelity? In other words, is a bump box a must?