SRPP Amplifier
     Moving the output from the bottom tube's plate to the top tube's cathode transforms the actively loaded grounded-cathode amplifier into the SRPP. Thus, all the same tricks and topological variations apply to this circuit as did to the actively loaded grounded-cathode amplifier. See SRPP Deconstructed or SRPP Decoded or SRPP Once Again. Understand that in a phono preamp, the SRPP functions more as a pure voltage amplifier and less as a power amplifier, so that much of the criticisms lodged at the SRPP do not apply in this application.) 

     Two topological variations present themselves: the auto bias version, shown above and the fixed-bias version shown below.

     While the SRPP offers a much lower output impedance than the grounded-cathode amplifier, it is more sensitive to reactive loads. Consequently, the passive equalization's  impedance values should be kept high (i.e. high resistor values and low capacitor values), which unfortunately will increase the noise from the equalization network. Possibly the best technique might be to preload the SRPP's output with a low-valued fixed resistance to shunt out much of the network's varying impedance, say 10k, or whatever value yields the lowest distortion. 

     The danger hidden in any multi-tube circuit that holds one tube atop the other is the chance of exceeding the maximum cathode-to-heater voltage of the tube, usually about 100 volts. The workaround is to use two heater power supplies, one referenced to ground (or a few tens of volts above ground) and the other referenced to some higher voltage, such as 120 volts.

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