Sabai
It would be more realistic to say 2 Symphony pros but the performance of one Symphony pro was way more obvious than one QX4 sadly. The QX4 when turned on is very subtle, one has to really observe the changes that are occurring. The one positive bonus the Qx4 has over the S pro is the it has a power out so you can attach it to other devices like a power conditioner like I did. This creates a secondary field effect through the AC path. But at end of the day I have say the Symphony pro was better at immediately providing its sonic benefits and more of them.