Как определить, установлена ли звуковая карта?

Вариант 1:

{ ... }
if WaveOutGetNumDevs > 0 then
  ShowMessage('Wave-Device present')
else
  ShowMessage('No Wave-Device present');
{ ... }

Вариант 2:

Source: Delphi Knowledge Base: https://www.baltsoft.com/

function IsSoundCardInstalled: Boolean;
type
  SCFunc = function: UInt; stdcall;
var
  LibInst: LongInt;
  EntryPoint: SCFunc;
begin
  Result := False;
  LibInst := LoadLibrary(PChar('winmm.dll'));
  try
    if LibInst <> 0 then
    begin
      EntryPoint := GetProcAddress(LibInst, 'waveOutGetNumDevs');
      if (EntryPoint <> 0) then
        Result := True;
    end;
  finally
    if (LibInst <> 0) then
      FreeLibrary(LibInst);
  end;
end;