DarkMX does not work with external Tor. It does not support the Tor authcookie when Tor is installed from the Torproject package repositories. I will not support the default location of the authcookie, nor will any of the networks connect. I trust the official Tor binary because it is the official open source binary from the Torproject themselves. I also do not need two Tor connections on one system.

I'm not on Debian atm so I can't test it. Double check your torrc. But if it still doesn't work stop/disable the Tor daemon and try running the Tor Browser Bundle instead. I know that's probably less than ideal but it's another option to try.  If you use torsocks and if I remember correctly, try:   alias torsocks="torsocks -P 9150"