Nothing wrong with the P3 or A23, Depending on how much space there is in the cabinet you might not need a fan. And depending on how hot the amplifier runs. However if you feel its getting too hot then it might be a good idea to look into getting some fans in the cabinet because heat is not a great friend to electronics. You can also find fans that have 12v triggers and temperature sensors to kick on when hitting a certain temperature although they will cost more than a standard computer fan on a wallwart.