@anon32364091 I think you may have found the panel. This looks exactly like what I can remember, except it appears to be powered down (I can’t see a power light).
Do you remember what kind of output this panel had? If it was AC, it’s very likely I had 4050s; if it was DC, I probably had 4051s on FWR. (I listened to a filtered DC 4051 and it sounded completely different from what I remember.)