Instrument audio output to next audio input (back view) gets too low volume

[Technetic]

When I connect the audio out cables (back view panel) from any source (instrument in this case), to the audio inputs of another instrument (instead of its own mix device by default), the output volume sounds too low in comparison to the default config, and I can't see how to correct this. Can any one has this problem and know how to solve it? thanks for your answer. I must clarify that the receiving instrument has the option of audio input so this signal can be processed through it.

[selig]

Which instrument? Many gain stages in Reason have built in headroom added, such as when you load a sample into NNXT (9 dB or so IIRC). Once you know the offset it’s simple to correct. To find the offset, run a sine tone of known level through the device and adjust to match the origin level, noting the offset - correct for it and you’re done.

[Technetic]

Which instrument? Many gain stages in Reason have built in headroom added, such as when you load a sample into NNXT (9 dB or so IIRC). Once you know the offset it’s simple to correct. To find the offset, run a sine tone of known level through the device and adjust to match the origin level, noting the offset - correct for it and you’re done.

Thank you for answering.
I guess I got to the problem root but not yet to the solution. I am using Reaktor as an instrument, so when I load the .ens instrument I want to use, then connect some external signal from another VSTi (in the back panel), then I edit the Reaktor instrument to add the correspondent audio inputs into the instrument's diagram, then the VSTi's audio output (through reaktor) gets low volume. But if I start the Reaktor editor from scratch and send the input audio signal direct to the audio output, then everything sounds normal. I guess the .ens I want to use has some processes that decrease the input signal, so I am going deeper in the instrument diagram to see what's going on.