diff --git a/src/audiomixerboard.cpp b/src/audiomixerboard.cpp
index bb9bfe47b3..63d80e9452 100644
--- a/src/audiomixerboard.cpp
+++ b/src/audiomixerboard.cpp
@@ -913,7 +913,7 @@ CAudioMixerBoard::CAudioMixerBoard ( QWidget* parent ) :
 
     vecAvgLevels.Init ( MAX_NUM_CHANNELS, 0.0f );
 
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         vecpChanFader[i] = new CChannelFader ( this );
         vecpChanFader[i]->Hide();
@@ -938,7 +938,7 @@ CAudioMixerBoard::CAudioMixerBoard ( QWidget* parent ) :
 
 CAudioMixerBoard::~CAudioMixerBoard()
 {
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         delete vecpChanFader[i];
     }
@@ -947,7 +947,7 @@ CAudioMixerBoard::~CAudioMixerBoard()
 template<unsigned int slotId>
 inline void CAudioMixerBoard::connectFaderSignalsToMixerBoardSlots()
 {
-    int iCurChanID = slotId - 1;
+    size_t iCurChanID = slotId - 1;
 
     void ( CAudioMixerBoard::*pGainValueChanged ) ( float, bool, bool, bool, double ) = &CAudioMixerBoardSlots<slotId>::OnChGainValueChanged;
 
@@ -1000,7 +1000,7 @@ void CAudioMixerBoard::SetGUIDesign ( const EGUIDesign eNewDesign )
     }
 
     // apply GUI design to child GUI controls
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         vecpChanFader[i]->SetGUIDesign ( eNewDesign );
     }
@@ -1009,7 +1009,7 @@ void CAudioMixerBoard::SetGUIDesign ( const EGUIDesign eNewDesign )
 void CAudioMixerBoard::SetMeterStyle ( const EMeterStyle eNewMeterStyle )
 {
     // apply GUI design to child GUI controls
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         vecpChanFader[i]->SetMeterStyle ( eNewMeterStyle );
     }
@@ -1019,7 +1019,7 @@ void CAudioMixerBoard::SetDisplayPans ( const bool eNDP )
 {
     bDisplayPans = eNDP;
 
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         vecpChanFader[i]->SetDisplayPans ( eNDP && bIsPanSupported );
     }
@@ -1037,7 +1037,7 @@ void CAudioMixerBoard::HideAll()
     StoreAllFaderSettings();
 
     // make all controls invisible
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         vecpChanFader[i]->SetChannelLevel ( 0 );
         vecpChanFader[i]->SetDisplayChannelLevel ( false );
@@ -1081,49 +1081,50 @@ void CAudioMixerBoard::ChangeFaderOrder ( const EChSortType eChSortType )
     QMutexLocker locker ( &Mutex );
 
     // create a pair list of lower strings and fader ID for each channel
-    QList<QPair<QString, int>> PairList;
-    int                        iNumVisibleFaders = 0;
-    int                        iMyFader          = -1;
+    QList<QPair<QString, size_t>> PairList;
+    int                           iNumVisibleFaders = 0;
+    int                           iMyFader          = -1;
 
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         if ( vecpChanFader[i]->GetIsMyOwnFader() )
         {
-            iMyFader = i;
+            iMyFader = static_cast<int> ( i );
         }
 
         if ( eChSortType == ST_BY_NAME )
         {
-            PairList << QPair<QString, int> ( vecpChanFader[i]->GetReceivedName().toLower(), i );
+            PairList << QPair<QString, size_t> ( vecpChanFader[i]->GetReceivedName().toLower(), i );
         }
         else if ( eChSortType == ST_BY_CITY )
         {
-            PairList << QPair<QString, int> ( vecpChanFader[i]->GetReceivedCity().toLower(), i );
+            PairList << QPair<QString, size_t> ( vecpChanFader[i]->GetReceivedCity().toLower(), i );
         }
         else if ( eChSortType == ST_BY_INSTRUMENT )
         {
             // sort first "by instrument" and second "by name" by adding the name after the instrument
-            PairList << QPair<QString, int> ( CInstPictures::GetName ( vecpChanFader[i]->GetReceivedInstrument() ) +
-                                                  vecpChanFader[i]->GetReceivedName().toLower(),
-                                              i );
+            PairList << QPair<QString, size_t> ( CInstPictures::GetName ( vecpChanFader[i]->GetReceivedInstrument() ) +
+                                                     vecpChanFader[i]->GetReceivedName().toLower(),
+                                                 i );
         }
         else if ( eChSortType == ST_BY_GROUPID )
         {
             if ( vecpChanFader[i]->GetGroupID() == INVALID_INDEX )
             {
                 // put channels without a group at the end
-                PairList << QPair<QString, int> ( "z", i ); // group IDs are numbers, use letter to put it at the end
+                PairList << QPair<QString, size_t> ( "z", i ); // group IDs are numbers, use letter to put it at the end
             }
             else
             {
-                PairList << QPair<QString, int> ( QString::number ( vecpChanFader[i]->GetGroupID() ), i );
+                PairList << QPair<QString, size_t> ( QString::number ( vecpChanFader[i]->GetGroupID() ), i );
             }
         }
         else // ST_NO_SORT
         {
             // per definition for no sort: faders are sorted in the order they appeared (note that we
             // pad to a total of 11 characters with zeros to make sure the sorting is done correctly)
-            PairList << QPair<QString, int> ( QString ( "%1" ).arg ( vecpChanFader[i]->GetRunningNewClientCnt(), 11, 10, QLatin1Char ( '0' ) ), i );
+            PairList << QPair<QString, size_t> ( QString ( "%1" ).arg ( vecpChanFader[i]->GetRunningNewClientCnt(), 11, 10, QLatin1Char ( '0' ) ),
+                                                 i );
         }
 
         // count the number of visible faders
@@ -1141,7 +1142,7 @@ void CAudioMixerBoard::ChangeFaderOrder ( const EChSortType eChSortType )
     {
         for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
         {
-            if ( iMyFader == PairList[i].second )
+            if ( iMyFader == static_cast<int> ( PairList[i].second ) )
             {
                 PairList.move ( i, 0 );
                 break;
@@ -1160,7 +1161,7 @@ void CAudioMixerBoard::ChangeFaderOrder ( const EChSortType eChSortType )
 
     for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
-        const int iCurFaderID = PairList[i].second;
+        const size_t iCurFaderID = PairList[i].second;
 
         if ( vecpChanFader[iCurFaderID]->IsVisible() )
         {
@@ -1205,7 +1206,7 @@ void CAudioMixerBoard::SetRecorderState ( const ERecorderState newRecorderState
 void CAudioMixerBoard::ApplyNewConClientList ( CVector<CChannelInfo>& vecChanInfo )
 {
     // get number of connected clients
-    const int iNumConnectedClients = vecChanInfo.Size();
+    const size_t iNumConnectedClients = vecChanInfo.size();
 
     Mutex.lock();
     {
@@ -1219,22 +1220,26 @@ void CAudioMixerBoard::ApplyNewConClientList ( CVector<CChannelInfo>& vecChanInf
         // search for channels which are already present and preserve their gain
         // setting, for all other channels reset gain
 
-        // get all channels which are in use/not in use. We use the array index of vecChanInfo
-        // if the fader is in use, else INVALID_INDEX to specify it is not in use
+        // get all channels which are in use/not in use.
+        // We use the array index of vecChanInfo if the fader is in use,
+        // else INVALID_INDEX to specify it is not in use
+        // so must use "int" for the array type.
         int iFaderNumber[MAX_NUM_CHANNELS];
 
-        for ( int iChanID = 0; iChanID < MAX_NUM_CHANNELS; iChanID++ )
+        for ( size_t iChanID = 0; iChanID < MAX_NUM_CHANNELS; iChanID++ )
         {
             iFaderNumber[iChanID] = INVALID_INDEX;
         }
 
-        for ( int iFader = 0; iFader < iNumConnectedClients; iFader++ )
+        for ( size_t iFader = 0; iFader < iNumConnectedClients; iFader++ )
         {
-            iFaderNumber[vecChanInfo[iFader].iChanID] = iFader;
+            // ideally "iChanID" in CChannelInfo would be size_t if it can never be INVALID_INDEX
+            // as assumed here
+            iFaderNumber[vecChanInfo[iFader].iChanID] = static_cast<int> ( iFader );
         }
 
         // Hide all unused faders and initialize used ones
-        for ( int iChanID = 0; iChanID < MAX_NUM_CHANNELS; iChanID++ )
+        for ( size_t iChanID = 0; iChanID < MAX_NUM_CHANNELS; iChanID++ )
         {
             if ( iFaderNumber[iChanID] == INVALID_INDEX )
             {
@@ -1244,6 +1249,7 @@ void CAudioMixerBoard::ApplyNewConClientList ( CVector<CChannelInfo>& vecChanInf
                 vecpChanFader[iChanID]->Hide();
                 continue;
             }
+            size_t idxVecpChan = static_cast<size_t> ( iFaderNumber[iChanID] );
 
             // current fader is used
             if ( !vecpChanFader[iChanID]->IsVisible() )
@@ -1253,7 +1259,7 @@ void CAudioMixerBoard::ApplyNewConClientList ( CVector<CChannelInfo>& vecChanInf
                 vecpChanFader[iChanID]->Reset();
                 vecAvgLevels[iChanID] = 0.0f;
 
-                if ( iChanID == iMyChannelID )
+                if ( static_cast<int> ( iChanID ) == iMyChannelID )
                 {
                     // this is my own fader --> set fader property
                     vecpChanFader[iChanID]->SetIsMyOwnFader();
@@ -1274,7 +1280,7 @@ void CAudioMixerBoard::ApplyNewConClientList ( CVector<CChannelInfo>& vecChanInf
                 // we can adjust the level even if no fader was visible.
                 // The fader level of 100 % is the default in the
                 // server, in that case we do not have to do anything here.
-                if ( ( !bNoFaderVisible || ( ( iMyChannelID != INVALID_INDEX ) && ( iMyChannelID != iChanID ) ) ) &&
+                if ( ( !bNoFaderVisible || ( ( iMyChannelID != INVALID_INDEX ) && ( iMyChannelID != static_cast<int> ( iChanID ) ) ) ) &&
                      ( pSettings->iNewClientFaderLevel != 100 ) )
                 {
                     // the value is in percent -> convert range
@@ -1282,7 +1288,7 @@ void CAudioMixerBoard::ApplyNewConClientList ( CVector<CChannelInfo>& vecChanInf
                 }
             }
 
-            if ( vecpChanFader[iChanID]->GetReceivedName().compare ( vecChanInfo[iFaderNumber[iChanID]].strName ) )
+            if ( vecpChanFader[iChanID]->GetReceivedName().compare ( vecChanInfo[idxVecpChan].strName ) )
             {
                 // the text has actually changed, search in the list of
                 // stored settings if we have a matching entry
@@ -1292,7 +1298,7 @@ void CAudioMixerBoard::ApplyNewConClientList ( CVector<CChannelInfo>& vecChanInf
                 bool bStoredFaderIsMute;
                 int  iGroupID;
 
-                if ( GetStoredFaderSettings ( vecChanInfo[iFaderNumber[iChanID]].strName,
+                if ( GetStoredFaderSettings ( vecChanInfo[idxVecpChan].strName,
                                               iStoredFaderLevel,
                                               iStoredPanValue,
                                               bStoredFaderIsSolo,
@@ -1308,7 +1314,7 @@ void CAudioMixerBoard::ApplyNewConClientList ( CVector<CChannelInfo>& vecChanInf
             }
 
             // set the channel infos
-            vecpChanFader[iChanID]->SetChannelInfos ( vecChanInfo[iFaderNumber[iChanID]] );
+            vecpChanFader[iChanID]->SetChannelInfos ( vecChanInfo[idxVecpChan] );
         }
 
         // update the solo states since if any channel was on solo and a new client
@@ -1324,7 +1330,7 @@ void CAudioMixerBoard::ApplyNewConClientList ( CVector<CChannelInfo>& vecChanInf
     ChangeFaderOrder ( eChSortType );
 
     // emit status of connected clients
-    emit NumClientsChanged ( iNumConnectedClients );
+    emit NumClientsChanged ( static_cast<int> ( iNumConnectedClients ) );
 }
 
 void CAudioMixerBoard::SetFaderLevel ( const int iChannelIdx, const int iValue )
@@ -1332,9 +1338,9 @@ void CAudioMixerBoard::SetFaderLevel ( const int iChannelIdx, const int iValue )
     // only apply new fader level if channel index is valid and the fader is visible
     if ( ( iChannelIdx >= 0 ) && ( iChannelIdx < MAX_NUM_CHANNELS ) )
     {
-        if ( vecpChanFader[iChannelIdx]->IsVisible() )
+        if ( vecpChanFader[static_cast<size_t> ( iChannelIdx )]->IsVisible() )
         {
-            vecpChanFader[iChannelIdx]->SetFaderLevel ( iValue );
+            vecpChanFader[static_cast<size_t> ( iChannelIdx )]->SetFaderLevel ( iValue );
         }
     }
 }
@@ -1344,9 +1350,9 @@ void CAudioMixerBoard::SetPanValue ( const int iChannelIdx, const int iValue )
     // only apply new pan value if channel index is valid and the panner is visible
     if ( ( iChannelIdx >= 0 ) && ( iChannelIdx < MAX_NUM_CHANNELS ) && bDisplayPans )
     {
-        if ( vecpChanFader[iChannelIdx]->IsVisible() )
+        if ( vecpChanFader[static_cast<size_t> ( iChannelIdx )]->IsVisible() )
         {
-            vecpChanFader[iChannelIdx]->SetPanValue ( iValue );
+            vecpChanFader[static_cast<size_t> ( iChannelIdx )]->SetPanValue ( iValue );
         }
     }
 }
@@ -1357,9 +1363,9 @@ void CAudioMixerBoard::SetFaderIsSolo ( const int iChannelIdx, const bool bIsSol
     if ( ( iChannelIdx >= 0 ) && ( iChannelIdx < MAX_NUM_CHANNELS ) )
 
     {
-        if ( vecpChanFader[iChannelIdx]->IsVisible() )
+        if ( vecpChanFader[static_cast<size_t> ( iChannelIdx )]->IsVisible() )
         {
-            vecpChanFader[iChannelIdx]->SetFaderIsSolo ( bIsSolo );
+            vecpChanFader[static_cast<size_t> ( iChannelIdx )]->SetFaderIsSolo ( bIsSolo );
         }
     }
 }
@@ -1369,9 +1375,9 @@ void CAudioMixerBoard::SetFaderIsMute ( const int iChannelIdx, const bool bIsMut
     // only apply mute if channel index is valid and the fader is visible
     if ( ( iChannelIdx >= 0 ) && ( iChannelIdx < MAX_NUM_CHANNELS ) )
     {
-        if ( vecpChanFader[iChannelIdx]->IsVisible() )
+        if ( vecpChanFader[static_cast<size_t> ( iChannelIdx )]->IsVisible() )
         {
-            vecpChanFader[iChannelIdx]->SetFaderIsMute ( bIsMute );
+            vecpChanFader[static_cast<size_t> ( iChannelIdx )]->SetFaderIsMute ( bIsMute );
         }
     }
 }
@@ -1380,10 +1386,10 @@ void CAudioMixerBoard::SetAllFaderLevelsToNewClientLevel()
 {
     QMutexLocker locker ( &Mutex );
 
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         // only apply to visible faders and not to my own channel fader
-        if ( vecpChanFader[i]->IsVisible() && ( i != iMyChannelID ) )
+        if ( vecpChanFader[i]->IsVisible() && ( static_cast<int> ( i ) != iMyChannelID ) )
         {
             // the value is in percent -> convert range, also use the group
             // update flag to make sure the group values are all set to the
@@ -1409,19 +1415,19 @@ void CAudioMixerBoard::AutoAdjustAllFaderLevels()
     levels.resize ( MAX_NUM_FADER_GROUPS + 1 );
 
     // compute min/max level per group and number of channels per group
-    for ( int i = 0; i < MAX_NUM_CHANNELS; ++i )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; ++i )
     {
         // only apply to visible faders (and not to my own channel fader)
-        if ( vecpChanFader[i]->IsVisible() && ( i != iMyChannelID ) )
+        if ( vecpChanFader[i]->IsVisible() && ( static_cast<int> ( i ) != iMyChannelID ) )
         {
             // map averaged meter output level to decibels
             // (invert CStereoSignalLevelMeter::CalcLogResultForMeter)
             float leveldB = vecAvgLevels[i] * ( UPPER_BOUND_SIG_METER - LOW_BOUND_SIG_METER ) / NUM_STEPS_LED_BAR + LOW_BOUND_SIG_METER;
 
-            int group = vecpChanFader[i]->GetGroupID();
-            if ( group == INVALID_INDEX )
+            size_t group = MAX_NUM_FADER_GROUPS;
+            if ( vecpChanFader[i]->GetGroupID() != INVALID_INDEX )
             {
-                group = MAX_NUM_FADER_GROUPS;
+                group = static_cast<size_t> ( vecpChanFader[i]->GetGroupID() );
             }
 
             if ( leveldB >= AUTO_FADER_NOISE_THRESHOLD_DB )
@@ -1434,7 +1440,7 @@ void CAudioMixerBoard::AutoAdjustAllFaderLevels()
     }
 
     // sort levels for later median computation
-    for ( int i = 0; i < MAX_NUM_FADER_GROUPS + 1; ++i )
+    for ( size_t i = 0; i < MAX_NUM_FADER_GROUPS + 1; ++i )
     {
         std::sort ( levels[i].begin(), levels[i].end() );
     }
@@ -1460,7 +1466,7 @@ void CAudioMixerBoard::AutoAdjustAllFaderLevels()
     float vecTargetChannelLevel[MAX_NUM_FADER_GROUPS + 1];
     float levelOffset = 0.0f;
     float minFader    = 0.0f;
-    for ( int i = 0; i < MAX_NUM_FADER_GROUPS + 1; ++i )
+    for ( size_t i = 0; i < MAX_NUM_FADER_GROUPS + 1; ++i )
     {
         // compute the target level for each channel in the current group
         // (prevent clipping when each channel in this group contributes at
@@ -1468,7 +1474,7 @@ void CAudioMixerBoard::AutoAdjustAllFaderLevels()
         vecTargetChannelLevel[i] = vecChannelsPerGroup[i] > 0 ? targetLevelPerGroup - 20.0f * log10 ( vecChannelsPerGroup[i] ) : 0.0f;
 
         // get median level
-        int cntChannels = levels[i].Size();
+        size_t cntChannels = levels[i].size();
         if ( cntChannels == 0 )
         {
             continue;
@@ -1499,10 +1505,10 @@ void CAudioMixerBoard::AutoAdjustAllFaderLevels()
     }
 
     // adjust all levels
-    for ( int i = 0; i < MAX_NUM_CHANNELS; ++i )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; ++i )
     {
         // only apply to visible faders (and not to my own channel fader)
-        if ( vecpChanFader[i]->IsVisible() && ( i != iMyChannelID ) )
+        if ( vecpChanFader[i]->IsVisible() && ( static_cast<int> ( i ) != iMyChannelID ) )
         {
             // map averaged meter output level to decibels
             // (invert CStereoSignalLevelMeter::CalcLogResultForMeter)
@@ -1547,7 +1553,7 @@ void CAudioMixerBoard::SetMIDICtrlUsed ( const bool bMIDICtrlUsed )
 {
     QMutexLocker locker ( &Mutex );
 
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         vecpChanFader[i]->SetMIDICtrlUsed ( bMIDICtrlUsed );
     }
@@ -1557,7 +1563,7 @@ void CAudioMixerBoard::StoreAllFaderSettings()
 {
     QMutexLocker locker ( &Mutex );
 
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         StoreFaderSettings ( vecpChanFader[i] );
     }
@@ -1573,7 +1579,7 @@ void CAudioMixerBoard::LoadAllFaderSettings()
     bool bStoredFaderIsMute;
     int  iGroupID;
 
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         if ( GetStoredFaderSettings ( vecpChanFader[i]->GetReceivedName(),
                                       iStoredFaderLevel,
@@ -1596,9 +1602,9 @@ void CAudioMixerBoard::SetRemoteFaderIsMute ( const int iChannelIdx, const bool
     // only apply remote mute state if channel index is valid and the fader is visible
     if ( ( iChannelIdx >= 0 ) && ( iChannelIdx < MAX_NUM_CHANNELS ) )
     {
-        if ( vecpChanFader[iChannelIdx]->IsVisible() )
+        if ( vecpChanFader[static_cast<size_t> ( iChannelIdx )]->IsVisible() )
         {
-            vecpChanFader[iChannelIdx]->SetRemoteFaderIsMute ( bIsMute );
+            vecpChanFader[static_cast<size_t> ( iChannelIdx )]->SetRemoteFaderIsMute ( bIsMute );
         }
     }
 }
@@ -1608,7 +1614,7 @@ void CAudioMixerBoard::UpdateSoloStates()
     // first check if any channel has a solo state active
     bool bAnyChannelIsSolo = false;
 
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         // check if fader is in use and has solo state active
         if ( vecpChanFader[i]->IsVisible() && vecpChanFader[i]->IsSolo() )
@@ -1619,7 +1625,7 @@ void CAudioMixerBoard::UpdateSoloStates()
     }
 
     // now update the solo state of all active faders
-    for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+    for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
     {
         if ( vecpChanFader[i]->IsVisible() )
         {
@@ -1635,6 +1641,7 @@ void CAudioMixerBoard::UpdateGainValue ( const int    iChannelIdx,
                                          const bool   bSuppressServerUpdate,
                                          const double dLevelRatio )
 {
+    size_t stChannelIdx = static_cast<size_t> ( iChannelIdx );
     // update current gain
     if ( !bSuppressServerUpdate )
     {
@@ -1644,13 +1651,13 @@ void CAudioMixerBoard::UpdateGainValue ( const int    iChannelIdx,
     // if this fader is selected, all other in the group must be updated as
     // well (note that we do not have to update if this is already a group update
     // to avoid an infinite loop)
-    if ( ( vecpChanFader[iChannelIdx]->GetGroupID() != INVALID_INDEX ) && !bIsGroupUpdate )
+    if ( ( vecpChanFader[stChannelIdx]->GetGroupID() != INVALID_INDEX ) && !bIsGroupUpdate )
     {
-        for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
+        for ( size_t i = 0; i < MAX_NUM_CHANNELS; i++ )
         {
             // update rest of faders selected
-            if ( vecpChanFader[i]->IsVisible() && ( vecpChanFader[i]->GetGroupID() == vecpChanFader[iChannelIdx]->GetGroupID() ) &&
-                 ( i != iChannelIdx ) && ( dLevelRatio >= 0 ) )
+            if ( vecpChanFader[i]->IsVisible() && ( vecpChanFader[i]->GetGroupID() == vecpChanFader[stChannelIdx]->GetGroupID() ) &&
+                 ( i != stChannelIdx ) && ( dLevelRatio >= 0 ) )
             {
                 // synchronize faders with moving fader level (it is important
                 // to set the group flag to avoid infinite looping)
@@ -1682,9 +1689,9 @@ void CAudioMixerBoard::StoreFaderSettings ( CChannelFader* pChanFader )
         pSettings->vecStoredFaderIsSolo[0]  = pChanFader->IsSolo();
         pSettings->vecStoredFaderIsMute[0]  = pChanFader->IsMute();
         pSettings->vecStoredFaderGroupID[0] = pChanFader->GetGroupID();
-        int iTempListCnt                    = 1; // current fader is on top, other faders index start at 1
+        size_t iTempListCnt                 = 1; // current fader is on top, other faders index start at 1
 
-        for ( int iIdx = 0; iIdx < MAX_NUM_STORED_FADER_SETTINGS; iIdx++ )
+        for ( size_t iIdx = 0; iIdx < MAX_NUM_STORED_FADER_SETTINGS; iIdx++ )
         {
             // first check if we still have space in our data storage
             if ( iTempListCnt < MAX_NUM_STORED_FADER_SETTINGS )
@@ -1692,7 +1699,7 @@ void CAudioMixerBoard::StoreFaderSettings ( CChannelFader* pChanFader )
                 // check for the old index of the current entry (this has to be
                 // skipped), note that per definition: the old index is an illegal
                 // index in case the entry was not present in the vector before
-                if ( iIdx != iOldIdx )
+                if ( static_cast<int> ( iIdx ) != iOldIdx )
                 {
                     pSettings->vecStoredFaderLevels[iTempListCnt]  = viOldStoredFaderLevels[iIdx];
                     pSettings->vecStoredPanValues[iTempListCnt]    = viOldStoredPanValues[iIdx];
@@ -1717,7 +1724,7 @@ bool CAudioMixerBoard::GetStoredFaderSettings ( const QString& strName,
     // only do the check if the name string is not empty
     if ( !strName.isEmpty() )
     {
-        for ( int iIdx = 0; iIdx < MAX_NUM_STORED_FADER_SETTINGS; iIdx++ )
+        for ( size_t iIdx = 0; iIdx < MAX_NUM_STORED_FADER_SETTINGS; iIdx++ )
         {
             // check if fader text is already known in the list
             if ( !pSettings->vecStoredFaderTags[iIdx].compare ( strName ) )
@@ -1741,10 +1748,10 @@ bool CAudioMixerBoard::GetStoredFaderSettings ( const QString& strName,
 
 void CAudioMixerBoard::SetChannelLevels ( const CVector<uint16_t>& vecChannelLevel )
 {
-    const int iNumChannelLevels = vecChannelLevel.Size();
-    int       i                 = 0;
+    const size_t iNumChannelLevels = vecChannelLevel.size();
+    size_t       i                 = 0;
 
-    for ( int iChId = 0; iChId < MAX_NUM_CHANNELS; iChId++ )
+    for ( size_t iChId = 0; iChId < MAX_NUM_CHANNELS; iChId++ )
     {
         if ( vecpChanFader[iChId]->IsVisible() && ( i < iNumChannelLevels ) )
         {
diff --git a/src/audiomixerboard.h b/src/audiomixerboard.h
index 47d4811512..ca048ad17f 100644
--- a/src/audiomixerboard.h
+++ b/src/audiomixerboard.h
@@ -266,7 +266,7 @@ class CAudioMixerBoard : public QGroupBox, public CAudioMixerBoardSlots<MAX_NUM_
     bool                    bDisplayPans;
     bool                    bIsPanSupported;
     bool                    bNoFaderVisible;
-    int                     iMyChannelID;
+    int                     iMyChannelID;         // must use int (not size_t) so INVALID_INDEX can be stored
     int                     iRunningNewClientCnt; // integer type is sufficient, will never overrun for its purpose
     int                     iNumMixerPanelRows;
     QString                 strServerName;