I would like to emphasize something that Elizabeth said, contact the manufacturer, but add that unless the inputs on the amp are user selectable switched inputs, you might need to rethink this arrangement. The non-operating unit, either your receiver or pre-amp, and their associated ICs may affect the sound quality, introduce noise, or both. Additionally, you may want to contact the receiver and pre-amp manufacturer to determine the affect on their components output stage, i.e., not cause any damage when subjected to this configuration in a long-term situation.
Anyway, these are some of the concerns that I would have with this configuration. Hopefully some EE will weigh in and provide a more definitive solution.
Anyway, these are some of the concerns that I would have with this configuration. Hopefully some EE will weigh in and provide a more definitive solution.