Depending on the specific cables and components that are involved the effects you have noted may be due to one or both of the following, which are not caused by the splitter itself:
1)The phono stage is now having to drive a lower impedance (i.e., a heavier load) than before. When both components that are being driven are turned on their combined load impedance as seen by the phono stage equals the product (multiplication) of their individual input impedances divided by the sum of their input impedances. Which will always be lower than either of the individual input impedances, and may be much lower. That effect will most likely be no better if one of them is turned off, and may actually be worse if one component is turned off because the input impedance of the unpowered component may to at least a slight degree fluctuate arbitrarily as a function of signal level.
2)The phono stage is now having to drive the capacitance of two sets of interconnect cables, rather than one. The capacitance of the cables to the tape deck will affect the signal received by the preamp or whatever other component is connected just as much as the capacitance of the cables to the preamp itself, since it will affect the signal as it exists at the output terminals of the phono stage. This effect is most likely to be significant if the output impedance of the phono stage is high at high frequencies, and if either or both of the cables are long and/or have high capacitance per unit length.
Again, neither of these effects are caused by the splitter itself. And FWIW I have used the AQ splitter in the past with fine results.
Regards,
-- Al
1)The phono stage is now having to drive a lower impedance (i.e., a heavier load) than before. When both components that are being driven are turned on their combined load impedance as seen by the phono stage equals the product (multiplication) of their individual input impedances divided by the sum of their input impedances. Which will always be lower than either of the individual input impedances, and may be much lower. That effect will most likely be no better if one of them is turned off, and may actually be worse if one component is turned off because the input impedance of the unpowered component may to at least a slight degree fluctuate arbitrarily as a function of signal level.
2)The phono stage is now having to drive the capacitance of two sets of interconnect cables, rather than one. The capacitance of the cables to the tape deck will affect the signal received by the preamp or whatever other component is connected just as much as the capacitance of the cables to the preamp itself, since it will affect the signal as it exists at the output terminals of the phono stage. This effect is most likely to be significant if the output impedance of the phono stage is high at high frequencies, and if either or both of the cables are long and/or have high capacitance per unit length.
Again, neither of these effects are caused by the splitter itself. And FWIW I have used the AQ splitter in the past with fine results.
Regards,
-- Al