Use the tape out jacks on the PAT-4 to access the output of the phono stage. That stage is located before those jacks in the circuitry, and of course before the second (line level) gain stage and the volume control. The volume control is located at the input of the line stage, both of which you want to avoid. The PAT phono stage produces about 40dB of gain, iirc.
If you can use a PAS-3 instead of a PAT-4, you may prefer it’s sound. PAS = tube, PAT = early solid state. If you prefer ss, the PAT-5 was significantly better than the PAT-4. Years ago Frank Van Alstine offered an excellent PAS modification, which cured the PAS’ ills. He did the same for the ARC SP-3.
