Is it safe

I talked to the tech at Jolida and they said it should not be a problem as long as only one source is operating at a time.However if I understand what Elizabeth is saying the problem is not so much in the amp as it is with the other source receiving a voltage on it's input.I assume that there is nothing in the circuit to prevent a back flow of current through the other source.Wolf_garcia the manual says "Only one input signal should be operating at one time,If both inputs are RECEIVING an input signal, the result will be distorted sound." the way it is worded makes it seem that it would be okay as long as I was only sending one signal at a time.I guess for right now until I know for sure I am not going to blow anything up it will be one source or time to get a preamp that handles more than one source.

Thank you everyone and Thank You Almarg for your well explained response. Once again I am amazed by the depth of knowledge and willingness of the members of this site to help each other out.It looks like with the potential to do harm, even in the long term to my equipment I am just going to bite the bullet and get a preamp.