The dbx 540 tube mic preamp 500 Series module is packed with tone-shaping options. A super-fast optical compressor provides you with full control over attack, release, and compression level. Its 12AX7 preamp tube is easily accessible, so swapping it out is a piece of cake. Dropping a vintage tube into the 540 gives it a completely different flavor. Switchable phantom power, phase invert, a selectable -20dB pad, and full metering yield the usability you demand. The front panel includes a handy TRS microphone input. Utilizing an LME49720 op-amp for excellent fidelity and smooth hand-machined controls, the dbx 540 is a stellar tube mic pre for your 500 Series rack!