Wow, you went all out. I just used the volume controls on the sound card and the Kenwood. For the isolation transformers I am pretty sure they are Radio Shack audio transformers with one side being called 8 ohm and the other either 1000 or 500 ohm depending on the taps used.
I think it depends on where you tap into the audio out from the rig. I didn¡¯t feel like drilling another hole in my case, so I use the headphone out. To do that, I had to use a low to high impedance transformer. After that, I used a Jfet buffer and a volume pot. For the transmit side I only use a buffer and volume control. Already worked several stations on FT-8 and PSK-31.
