Latency when controlling hardware instruments

Hello good people!
I know latency is not new subject here, but I couldn’t find anything helpful reading the existing posts about the subject.
The problem:
Having 1s+ latency when controlling external hardware synths.
If I use Dubler 2 with a V-Synth all goes well and latency is really minimum, but things are different when controlling a hardware synth. The latency happens only with Dubler. Other controllers, hardware or software work fine.
I use a MioXL as the midi interface and a Mac. Tested with all my synths, so it doesn’t look like a problem on my synths. Since other controllers work fine it doesn’t look like a MioXL issues either.
U’m clueless at this point.
Any ideas?

Hi Andre,

How are you routing the MIDI from Dubler to your hardware synths? Is it directly from the app or via your DAW? If you could send a screenshot of Dubler’s audio device settings we might be able to spot anything adding latency