Home theater bypass

To operate ether system all units must be on ?

I tried it and the protection circuit tripped on the Mac 275 twice ?

Please tell us exactly how you have this whole thing hooked up.  Something's wrong somewhere. 

Ok the DVD player is connected to the receiver with a hdmi and connected via the audio outs to the preamp inputs. The receiver preouts are connected to the preamps tuner inputs. The preamp is connected to the Mac then the speakers Maggie 1.7. 

To operate either system all units must be on ?

For stereo playback, only the source (CD player, turntable or tuner), cj preamp and Mac power amp need to be on, the Onkyo receiver can be off.
Before any playback using Onkyo receiver at the first time, you need to set the cj preamp volume to 12 o’clock and re-calibrate the speakers level setting via automatic speaker setup or adjust the front R/L speakers manually (see page 55-59 of Onkyo TX-SR805 Owner’s manual).