I don't have much experience with PC sound cards, I don't
know if sound cards are available with an output frequency
range up to about 45kHz.
If the sound card has line level outputs, a simple 2 resistor
voltage divider could be used to lower it to phono level
(the PC wouldn't do any RIAA EQ, it would just pass through
the unEQ'd signal from the 1/2 speed input, but with all
frequencies doubled, i.e., back to normal).
There would need to be a 1 time setup:
Use a test record with a 1kHz tone, record at 1/2 speed,
play at normal speed and use the PC software to set the
output level to be the same as the 1kHz tone played at
normal speed.
Kirk Bayne
fredblue - Just curious - Do you have any Matrix Encoded
Compact Cassettes or DynaQuad or Electro-Voice Stereo-4
Matrix Encoded LPs?