The original Tube MP made pro-caliber tube preamping available to ordinary musicians and home studios. The MP Studio goes a step further by adding a VU meter for better level control and ART's OPL (Output Protection Limiter), which controls and maintains the output peak signal to protect hard-disk recording systems and soundcards. The VU meter reflects the impact of the OPL circuitry when it is activated, which allows more effective fine tuning of the audio signal. It is a valuable tool for recording in project and home studios and can also function as a DI box with impedance matching and preamplification for line-level sources