Coming To An UnderstandingOnly going by your most recent post there is some confusion of terms...
It seems you use the word "signal" to refer both to audio and RF signals...
Here I mean audio signals. The RF signals currently travel the 150 ft coax from the xmtr to the antenna. Currently I use a 6' cable with a 3mm phono jack at the computer feeding the "balanced" audio input of the 5000 via the two RCA phone jacks.And the distances between points is difficult for me to visualize because you talked all at once about having the transmitter in a temporary location but later in a permanent more distant location using "feet" and "yards" as the estimated measures.
The transmitter is still in my 2nd floor workshop/studio while the antenna has been moved from just outside this room on our 2nd floor deck to its permanent location in my back lot which is about 150 yards from the transmitter's original location. I need to move the transmitter into its outdoor location on the antenna. This will eliminate the need for the 150 yards of coax transmission line, but I will still have the need to feed the audio signal 150 yards from the PC as well as use outdoor extension cords the same distance to power the transmitter, unless I choose a solar feed (less likely).
yards away
Putting all that aside, I will describe using wire (not wireless) to connect X-distance from the computer's audio output to the transmitter's audio input.
I will assume, based on the audio cable description I think you've made, that the computer's audio output is -10 dB (consumer level) unbalanced.
I honestly don't know.
The output is either stereo (2-cables) or monaural (1-cable).
It is 2 cables with RCA phone jacks coming off a 3mm phone jack.
IF the computer output is stereo, it is recommended to mix to mono so as to require a single audio cable to span the distance out to the transmitter.
A common mistake made when mixing stereo to mono is that people use a stereo splitter cable accessory to directly short the left and right channels together. This will introduce distortion and is not a technically proper way to mix two audio channels.
Not knowing your level of audio technical knowledge I will leave it to you to ask how to mix 2-to-1 if you are not sure.
Consider me asking, because I have no idea. I have never had any interest in music, only information.
Once you have an L+R (left-and-right-channel-mixed-to-mono) audio signal, a 1:1 600-ohm/600-ohm matching transformer is needed to convert unbalanced to balanced (2-wire: shield & center-conductor to 3-wire shield-and-two-conductors).
I have no idea. My original plan was to splice in 150 ft to the original 6 ft. cable I am currently using.The 3-wire balanced audio cable does not need to be microphone grade, which is designed with heavier shielding, but should be adequate for "line-level", which in our case is expected to be -10 dB consumer level. This cable should span the distance out to the transmitter location and can attach straight to the balanced line input of the AMT-5000 transmitter.
Special Note: Do not use the 2 RCA Audio Input Jacks on the AMT5000. You will find that a terminal block exists inside the transmitter enclosure with 3-screws: ground/audio-/audio+. This is a balanced mono input.
Ask any questions about this.
I think that I have asked all that I know to ask at this time. Thanks! 
