Pro-Ject Tube Box S2 Phono Pre-amplifierThe Tube Box S2 is the very first Pro Ject product to feature a fully discrete circuit design that eschews the use of any OpAmps. It's also is the first product to come with replaceable tubes for tube rolling and sound shaping. This offers an array of options to choose from and lets you alter the sound signature to your preference. Tube Box S2 offers a full, relaxed, laid back sound with lush mids, just like you would expect from any high quality tube