I don’t know how long it will take us to get to TG-linux compatibility, but if one were to snoop the USB bus, one would see setting internal reference out sends: ‘R’, 0x02, 0xC0. One might recognize 0xC0 as serial line internet protocol from way back.
Then one might set amplitude to maximum and observe ‘A’, 0x00, 0xC0.
One might finish by snooping to see that outputting 10 Hz sends ‘F’, 0x01, 0x00, 0x00, 0x00, 0xC0. One might then try 2560 Hz and see ‘F’, 0x00, 0x01, 0x00, 0x00, 0xC0.
One could then decide whether to wait for Signal Hound to implement Linux TG compatibility, or to forge on ahead.