They are identical sized desktop units with the same sound, performance and operation. Both have two identical SSL microphone, line, and instrument pre-amplifiers capable of up to 62dB of microphone gain. This is more than enough mic gain for low output ribbon or vintage dynamic mics. Three separate push-button switches for Channels 1 and 2 select: +48-volt, line level, or instrument input for guitars and/or basses.

I liked the straight ahead input level metering provided by five LEDs that show the input level from -40 to 0dB--the manual offers good suggestions about setting record levels with the red Gain control knob. Lastly, there is a lighted "4K" button that adds a combination of high-frequency boost and subtle harmonic distortion--the sound of SSL 4000-Series consoles. This works well for acoustic guitars, somber-sounding microphones, and some vocalists.

There is a large Volume control knob that sets speaker level out of two 1/4-inch TRS rear panel output jacks. There is a Monitor Mix blend control to balance between "Input"--the live audio coming in and "USB" or the audio returning from the DAW. While the SSL 2 is perfect for single operator usage, the SSL 2+ is designed for collaborative sessions.

The SSL 2+ adds: MIDI input and output on 5-pin DIN jacks; an unbalanced stereo output that "mirrors" the main balanced 1&2 outputs; and another unbalanced stereo output 3&4, whose level is controlled back in the DAW. The SSL 2+ has a second stereo headphone output jack on the rear panel called Phones B with its own front panel level control.

Complete with the SSL Production Pack Bundle of software and USB cables, the SSL 2 sells for $229.99 MSRP and the SSL 2+ is $279.99 MSRP. They both come with excellent manuals that explain everything and offer good suggestions making these interfaces perfect for beginners.

Currently, I have purchased the SSL 2 and use it with a Microphone-Parts.com S-87 Microphone Kit I built. I use this setup with a pair of IK Multimedia iLoud MTM Reference Monitors.