vis_ngm.dll is an example of a Winamp visualization plugin.
vis_avs.dll is the file for the Advanced Visualization Studio (AVS) plugin.

procedure TForm1.FormShow(Sender: TObject);
var
   i : integer;
 //  BassAddonInfo : TBassAddonInfo;
   MIDI_FONTINFO : TMIDI_FONTINFO;
   UnloadedNames : string;
begin
   BassPlayer1 := TBassPlayer.Create(Self);

 // Check if required DLL's are succefully loaded.
   if BassPlayer1.BASSDLLVer = '' then
   begin
      Application.MessageBox('BASS.DLL is not loaded.', 'Confirm', MB_OK or MB_ICONINFORMATION);
      exit;
   end;

   UnloadedNames := '';
   if not BassPlayer1.BASSWMAReady then UnloadedNames := 'BASSWMA.DLL';
   if not BassPlayer1.BASSCDReady then
      if UnloadedNames = '' then
         UnloadedNames := 'BASSCD.DLL'
      else
         UnloadedNames := UnloadedNames + ', BASSCD.DLL';
   if not BassPlayer1.BASSMIDIReady then
      if UnloadedNames = '' then
         UnloadedNames := 'BASSMIDI.DLL'
       else
         UnloadedNames := UnloadedNames + ', BASSMIDI.DLL';
   if UnloadedNames <> '' then
      Application.MessageBox(pchar('Following BASS Library(s) is(are) not loaded.' + char(10) +
                           char(10) + UnloadedNames), 'Confirm', MB_OK or MB_ICONINFORMATION);

   BassPlayer1.OnNewFFTData := DisplayFFTBand;
   BassPlayer1.OnPluginStartPlay := PluginStartPlay;
   BassPlayer1.OnGetChannelInfo := PluginChannelInfo;
   BassPlayer1.OnGetMeta := GetMETAFromNet;
   BassPlayer1.OnGetLyric := GetMIDILyric;
   BassPlayer1.OnDownloaded := DownloadEnded;
   BassPlayer1.OnModeChange := ModeChanged;
   BassPlayer1.OnVisWindowShow := GetVisPluginInfo;
   BassPlayer1.OnPluginRequest := ProcessPluginRequest;

   ScrollBar1.Position := BassPlayer1.Volume;
   CreateBasicImage;
   ShowBackground;
   for i := 1 to NumFFTBands do
      PeakValue[i] := 0;

   // These components have been replaced and can be assigned new values.
   EQGains[0] := TrackBar1.Position - 15;
   EQGains[1] := TrackBar2.Position - 15;
   EQGains[2] := TrackBar3.Position - 15;
   EQGains[3] := TrackBar4.Position - 15;
   EQGains[4] := TrackBar5.Position - 15;
   EQGains[5] := TrackBar6.Position - 15;
   EQGains[6] := TrackBar7.Position - 15;
   EQGains[7] := TrackBar8.Position - 15;
   EQGains[8] := TrackBar9.Position - 15;
   EQGains[9] := TrackBar10.Position - 15;

   TrackBar11.Position := BassPlayer1.EchoLevel;
   TrackBar12.Position := BassPlayer1.ReverbLevel;

   if BassPlayer1.PlayerReady then
   begin
      //LoadWinampPlugin('in_cdda.dll');
      //LoadWinampPlugin('in_asf.dll');
      LoadWinampPlugin(ProgDir + 'Data\Plugins\in_midi.dll');   // I have found that it is unable to load in_midi v3.16.
        // So, I use in_midi v3.07.

      //LoadWinampPlugin('in_wm_old.dll');

      BassPlayer1.PluginFirst := false;

    // Following sentences are for supporting BASSMDID
      if BassPlayer1.BASSMIDIReady then
         if FileExists(ProgDir + 'Data\Plugins\Chorium.SF2') then
         begin
         // You can use any SF2 soundfont other than Chorium.SF2 to activate BASSMIDI.dll.
         // However this demo program requires Chorium.SF2.
            if BassPlayer1.MIDIFontInit(ProgDir + 'Data\Plugins\Chorium.SF2', MIDI_FONTINFO) then
            begin
               if BassPlayer1.MIDISoundReady then
                  InfoMemo.Lines.Add('MIDI sound ready !');

               InfoMemo.Lines.Add('MIDI soundfont Chorium.SF2 loaded');
               InfoMemo.Lines.Add(' Name : ' + MIDI_FONTINFO.FontName);
               InfoMemo.Lines.Add(' Presets : ' + formatFloat('#,##0', MIDI_FONTINFO.Presets));
               InfoMemo.Lines.Add(' Sample Size : ');
               InfoMemo.Lines.Add('         ' + formatFloat('#,##0', MIDI_FONTINFO.SampleSize) + ' bytes');
            end
         end else
         begin
            InfoMemo.Lines.Add('Cannot support BASS MIDI plugin because MIDI soundfont'#10 +
                               ' "Chorium.SF2" does not exist in the <Program_Directory>\Plugins directory.');
         end;

      if BassPlayer1.VisDrawerReady then
         BassPlayer1.UseVisDrawer := true
      else
      begin
         VisControlForm.UseWinampLook.Checked := false;
         VisControlForm.UseWinampLook.Enabled := false;
         Application.MessageBox('Gen_VisDrawer.DLL does not exist or not loaded.'#10 +
                                'Winamp-like visualization form is not supported.', 'Confirm',
                                MB_OK or MB_ICONINFORMATION);
      end;

   end;

   cbSingleChannelMode.Checked := BassPlayer1.SingleChannel;
   CurVisWindowAttr.VisHandle := 0;
   CurVisWindowAttr.VisType := Unavailable;

   VisPanel_Handle := VisPanel.Handle;
   if cbMergeVisWindow.Checked then
       BassPlayer1.VisEmbedHandle := VisPanel_Handle
    else
       BassPlayer1.VisEmbedHandle := 0;
   if BassPlayer1.VisEMBEDSwitchMode = WindowMove then
      cbEMBEDSwitchMode.Checked := true
   else
      cbEMBEDSwitchMode.Checked := false;

   if BassPlayer1.PlayerReady then
      Timer1.Enabled := true;

   Saved8087CW := Default8087CW;
   Set8087CW($133f);  // Disable all fpu exceptions

   ComboBox1.Items.LoadFromFile(ProgDir +  'Data\URL\lst.ini');
   ComboBox1.ItemIndex := 0;
end;

DSP_CHMX.DLL the plug-in DLL file
DSP_CHMX.HLP Channel Mixer help file
DSP_CHMX.INI configuration file
DSP_CHMX.TXT Channel Mixer overview