One thing people forget is the original DOD preamp 250’s all sound different. They just threw in parts. So it hard to know what version they copied or what’s in the gray one in the video.
Have a look. Top one is a gray unit. Notice the bottom one has a green cap. I changed it because it sounded like crap when I got it 30 years ago. I noticed all of the other ones had a different cap in that spot, so I replaced it. Boom, it sounded better. Notice I removed the battery jack out of two of them. Another thing I did 30 years ago
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