diff --git a/source/backend/plugin/CarlaPluginAU.cpp b/source/backend/plugin/CarlaPluginAU.cpp
index 675b8ae5c..8660883bc 100644
--- a/source/backend/plugin/CarlaPluginAU.cpp
+++ b/source/backend/plugin/CarlaPluginAU.cpp
@@ -260,11 +260,8 @@ public:
                                        kAudioUnitProperty_SupportedNumChannels,
                                        kAudioUnitScope_Global,
                                        0, &outDataSize, &outWritable) == noErr
-            /*
             && outDataSize != 0
-            && outDataSize % sizeof(AUChannelInfo) == 0
-            */
-            )
+            && outDataSize % sizeof(AUChannelInfo) == 0)
         {
             const uint32_t numChannels = outDataSize / sizeof(AUChannelInfo);
             AUChannelInfo* const channelInfo = new AUChannelInfo[numChannels];
@@ -279,12 +276,17 @@ public:
             {
                 AUChannelInfo* highestInfo = &channelInfo[0];
 
-                carla_stdout("getProperty returns {%u,%u}... config",
+                carla_stdout("kAudioUnitProperty_SupportedNumChannels returns {%d,%d}... config",
                              channelInfo[0].inChannels,
                              channelInfo[0].outChannels);
 
-                for (uint32_t i=1; i<numChannels; ++i)
+                for (uint32_t i=0; i<numChannels; ++i)
                 {
+                    if (channelInfo[i].inChannels < 0)
+                        channelInfo[i].inChannels = 2;
+                    if (channelInfo[i].outChannels < 0)
+                        channelInfo[i].outChannels = 2;
+
                     if (channelInfo[i].inChannels > highestInfo->inChannels
                         && channelInfo[i].outChannels > highestInfo->outChannels)
                     {
@@ -292,20 +294,69 @@ public:
                     }
                 }
 
-                audioIns = highestInfo->inChannels;
-                audioOuts = highestInfo->outChannels;
+                audioIns = std::min<int16_t>(64, highestInfo->inChannels);
+                audioOuts = std::min<int16_t>(64, highestInfo->outChannels);
             }
             else
             {
-                carla_stdout("getProperty failed");
+                carla_stdout("kAudioUnitProperty_SupportedNumChannels failed");
             }
 
             delete[] channelInfo;
         }
         else
         {
-            carla_stdout("kAudioUnitProperty_SupportedNumChannels returns no configs, assume stereo");
-            audioIns = audioOuts = 2;
+            outDataSize = 0;
+            if (fFunctions.getPropertyInfo(fInterface,
+                                           kAudioUnitProperty_ElementCount,
+                                           kAudioUnitScope_Input,
+                                           0, &outDataSize, &outWritable) == noErr
+                && outDataSize == sizeof(UInt32))
+            {
+                UInt32 count = 0;
+                if (fFunctions.getProperty(fInterface,
+                                           kAudioUnitProperty_ElementCount,
+                                           kAudioUnitScope_Input,
+                                           0, &count, &outDataSize) == noErr
+                    && outDataSize == sizeof(UInt32) && count != 0)
+                {
+                    AudioStreamBasicDescription desc;
+                    std::memset(&desc, 0, sizeof(desc));
+                    outDataSize = sizeof(AudioStreamBasicDescription);
+
+                    if (fFunctions.getProperty(fInterface,
+                                               kAudioUnitProperty_StreamFormat,
+                                               kAudioUnitScope_Input,
+                                               0, &desc, &outDataSize) == noErr)
+                        audioIns = std::min<uint32_t>(64, desc.mChannelsPerFrame);
+                }
+            }
+
+            outDataSize = 0;
+            if (fFunctions.getPropertyInfo(fInterface,
+                                           kAudioUnitProperty_ElementCount,
+                                           kAudioUnitScope_Output,
+                                           0, &outDataSize, &outWritable) == noErr
+                && outDataSize == sizeof(UInt32))
+            {
+                UInt32 count = 0;
+                if (fFunctions.getProperty(fInterface,
+                                           kAudioUnitProperty_ElementCount,
+                                           kAudioUnitScope_Output,
+                                           0, &count, &outDataSize) == noErr
+                    && outDataSize == sizeof(UInt32) && count != 0)
+                {
+                    AudioStreamBasicDescription desc;
+                    std::memset(&desc, 0, sizeof(desc));
+                    outDataSize = sizeof(AudioStreamBasicDescription);
+
+                    if (fFunctions.getProperty(fInterface,
+                                               kAudioUnitProperty_StreamFormat,
+                                               kAudioUnitScope_Output,
+                                               0, &desc, &outDataSize) == noErr)
+                        audioOuts = std::min<uint32_t>(64, desc.mChannelsPerFrame);
+                }
+            }
         }
 
         if (audioIns > 0)
diff --git a/source/discovery/carla-discovery.cpp b/source/discovery/carla-discovery.cpp
index 5ab21dd35..440064ccf 100644
--- a/source/discovery/carla-discovery.cpp
+++ b/source/discovery/carla-discovery.cpp
@@ -2182,8 +2182,13 @@ static bool do_au_check(const char* const filename, const bool doInit)
                 {
                     AUChannelInfo* highestInfo = &channelInfo[0];
 
-                    for (uint32_t i=1; i<numChannels; ++i)
+                    for (uint32_t i=0; i<numChannels; ++i)
                     {
+                        if (channelInfo[i].inChannels < 0)
+                            channelInfo[i].inChannels = 2;
+                        if (channelInfo[i].outChannels < 0)
+                            channelInfo[i].outChannels = 2;
+
                         if (channelInfo[i].inChannels > highestInfo->inChannels
                             && channelInfo[i].outChannels > highestInfo->outChannels)
                         {
@@ -2191,12 +2196,70 @@ static bool do_au_check(const char* const filename, const bool doInit)
                         }
                     }
 
-                    audioIns = highestInfo->inChannels;
-                    audioOuts = highestInfo->outChannels;
+                    audioIns = std::min<int16_t>(64, highestInfo->inChannels);
+                    audioOuts = std::min<int16_t>(64, highestInfo->outChannels);
                 }
 
                 delete[] channelInfo;
             }
+            else
+            {
+                // unsupported for now
+                interface->Close(interface);
+                continue;
+
+                outDataSize = 0;
+                if (auGetPropertyInfo(interface,
+                                      kAudioUnitProperty_ElementCount,
+                                      kAudioUnitScope_Input,
+                                      0, &outDataSize, &outWritable) == noErr
+                    && outDataSize == sizeof(UInt32))
+                {
+                    UInt32 count = 0;
+                    if (auGetProperty(interface,
+                                      kAudioUnitProperty_ElementCount,
+                                      kAudioUnitScope_Input,
+                                      0, &count, &outDataSize) == noErr
+                        && outDataSize == sizeof(UInt32) && count != 0)
+                    {
+                        AudioStreamBasicDescription desc;
+                        std::memset(&desc, 0, sizeof(desc));
+                        outDataSize = sizeof(AudioStreamBasicDescription);
+
+                        if (auGetProperty(interface,
+                                          kAudioUnitProperty_StreamFormat,
+                                          kAudioUnitScope_Input,
+                                          0, &desc, &outDataSize) == noErr)
+                            audioIns = std::min<uint32_t>(64, desc.mChannelsPerFrame);
+                    }
+                }
+
+                outDataSize = 0;
+                if (auGetPropertyInfo(interface,
+                                      kAudioUnitProperty_ElementCount,
+                                      kAudioUnitScope_Output,
+                                      0, &outDataSize, &outWritable) == noErr
+                    && outDataSize == sizeof(UInt32))
+                {
+                    UInt32 count = 0;
+                    if (auGetProperty(interface,
+                                      kAudioUnitProperty_ElementCount,
+                                      kAudioUnitScope_Output,
+                                      0, &count, &outDataSize) == noErr
+                        && outDataSize == sizeof(UInt32) && count != 0)
+                    {
+                        AudioStreamBasicDescription desc;
+                        std::memset(&desc, 0, sizeof(desc));
+                        outDataSize = sizeof(AudioStreamBasicDescription);
+
+                        if (auGetProperty(interface,
+                                          kAudioUnitProperty_StreamFormat,
+                                          kAudioUnitScope_Output,
+                                          0, &desc, &outDataSize) == noErr)
+                            audioOuts = std::min<uint32_t>(64, desc.mChannelsPerFrame);
+                    }
+                }
+            }
 
             // parameter count
             outDataSize = 0;
@@ -2292,17 +2355,7 @@ static bool do_au_check(const char* const filename, const bool doInit)
 
             if (doInit)
             {
-                // test valid scopes
-                outDataSize = 0;
-                if (auGetPropertyInfo(interface, kAudioUnitProperty_ElementCount, kAudioUnitScope_Input, 0, &outDataSize, &outWritable) == noErr && outDataSize == sizeof(UInt32))
-                {
-                    UInt32 count = 0;
-                    if (auGetProperty(interface, kAudioUnitProperty_ElementCount, kAudioUnitScope_Input, 0, &count, &outDataSize) == noErr && outDataSize == sizeof(UInt32) && count != 0)
-                    {
-                    }
-                }
-
-                // TODO
+                // TODO tests
             }
 
             const CFIndex componentNameLen = CFStringGetLength(componentName);
diff --git a/source/utils/CarlaStateUtils.cpp b/source/utils/CarlaStateUtils.cpp
index 419991ae0..8a87da853 100644
--- a/source/utils/CarlaStateUtils.cpp
+++ b/source/utils/CarlaStateUtils.cpp
@@ -1,6 +1,6 @@
 /*
  * Carla State utils
- * Copyright (C) 2012-2023 Filipe Coelho <falktx@falktx.com>
+ * Copyright (C) 2012-2024 Filipe Coelho <falktx@falktx.com>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
@@ -310,7 +310,7 @@ bool CarlaStateSave::fillFromXmlElement(const XmlElement* const xmlElement)
                     name = xmlSafeStringCharDup(text, false);
                 else if (tag == "Label" || tag == "URI" || tag == "Identifier" || tag == "Setup")
                     label = xmlSafeStringCharDup(text, false);
-                else if (tag == "Binary" || tag == "Filename")
+                else if (tag == "Binary" || tag == "Bundle" || tag == "Filename")
                     binary = xmlSafeStringCharDup(text, false);
                 else if (tag == "UniqueID")
                     uniqueId = text.getLargeIntValue();
@@ -594,6 +594,7 @@ void CarlaStateSave::dumpToMemoryStream(MemoryOutputStream& content) const
             infoXml << "   <Label>"    << xmlSafeString(label, true)  << "</Label>\n";
             break;
         case PLUGIN_AU:
+            infoXml << "   <Bundle>"   << xmlSafeString(binary, true) << "</Bundle>\n";
             infoXml << "   <Identifier>" << xmlSafeString(label, true) << "</Identifier>\n";
             break;
         case PLUGIN_CLAP: