Passive & Tubed pre-amps to power amp at same time?

Would any harm be done by using a Y-splitter to simultaneously connect a passive pre-amp and tubed pre-amp to the same power amp? The idea would be to use the passive for volume control and run signal from a CDP to the power amp. The tubed pre would be used for sending other inputs (e.g., phono) to the power amp. All devices would be "powered up" at the same time but only one input at a time would be used. Thanks in advance.