shntool is the easiest way...open the command prompt, navigate to the folder where the flacs are kept, enter "shntool join *.flac" this will join the flacs into a wav called "joined.wav" in the folder where the flacs are stored. so you should split them into different folders for each set so that the second set isn't appended to the first set. if you wanted to make it a flac, there is a switch to make the output a flac file, but i don't remember what it is.