I hope that it's not really your intention to apply 1vrms at 1kHz into the preamp phono input (that would be bad...). The input should be 5.5mv rms at 1kHz and conform to the RIAA preemphasis curve if you deviate from 1kHz. The output from the new phono stage is intended to be c.1vrms. Theoretically, the distortion should be more or less unmeasurable using the new design. However, it might be interesting to explore the overload characteristics.