Did they remove the little factory amp behind the radio when they installed the new one?
Also, is your HU a pioneer? If so, it runs on the opposite voltage of Toyota, so if the orange and white wire is hooked up, unplug it. (dimmer wire).
since i have amps, for the power antenna, i installed a switch to bring it up and down, i tapped the ACC wire so teh antenna will always go down when the power is off, but when it's on i can make it go up or down.

89 4Runner
3" BL, M/T locks, 33"bfg mt, bilstein, Kayline, tubebumper, toyotafiberglass panels
TBI: Elocker,3.4 w/ORS,b+b,S2Sstg2cams,arias pistons,P+P intake,TRDs/c,URDpullies+7th,downey headers,MAPECU2,WEGO WB, SupraMAF,walboro255,stg4clutch, EPaOo2 sim