I want to use the GM softsynth that comes with acid4 in Sonar, but what I think is it won't work with Directxer, what I've found is under the folder 'ACID' ->'MIDI' is that it?
The GM softsynth you are refering to, is that the Microsoft GM softsynth? If it is, then no, that won't work in Sonar. But in Sonar you have plenty of other options. You can use soundfonts (with LiveSynth Pro), other instruments, or the Edirol SoundCanvas (which sounds ALOT better than the GM softsynth).