         }
     }
 
-    static internal(set) var _engine = AVAudioEngine()
+    internal(set) static var _engine = AVAudioEngine()
 
     /// Reference to singleton MIDI
 
     #if !os(tvOS)
-    public static let midi = AKMIDI()
+        public static let midi = AKMIDI()
     #endif
 
-    @objc static var finalMixer = AKMixer()
+    @objc static var finalMixer: AKMixer?
 
     // MARK: - Device Management
 


    /// Disconnect all inputs
    @objc public static func disconnectAllInputs() {
        engine.disconnectNodeInput(finalMixer.avAudioNode)
    }
}

                }
            }
        #else
            // not available on ios
        #endif
    }

