I use a DangerDen Vario D5 and a Swiftech MCP655; they are the exact same pump. I find that they are very quiet and stay that way. I tried Laing DCC Ultra's (3 of them) and found them to be unreliable. The D5/MCP655 is a larger pump, but far more reliable and also very quiet. I sit mine on blocks of vibration gel. Excellent pumps and would recommend them.