The left side of the MDM-X4 is a six-channel mixer, with two mono sends, two stereo returns, and a monitor section. Channels 1 and 2 are balanced input XLR/¼" phone connectors. You'll have to have your own phantom power supply if you're going to use high-end microphones. Channels 3 through 6 are unbalanced ¼" phone connectors, as are the sends, returns, and the four individual track outputs. All are on a sunken flat panel pointing up. The stereo outs and the monitor outs are RCA jacks with standard MIDI In/Out/Thru jacks on the back panel pointing, well, back. Although seeing all the wires is not too pretty sometimes, I am one who appreciates the ease of making changes in the connections simply by leaning forward over the gently angled control surface and repatching from there. Lean to the right, and you'll see a small CPU-like fan on the side panel; don't worry, it's very quiet. A built-in power supply plugs into the wall using a non-removable, non-grounded cord.
Each of channels 1 through 4 has a trim pot, a line/mic or track input button, a send pot, a pan pot, two bus assign buttons (1/2 and 3/4), and a limited but capable 3-band equalizer. Channels 5 and 6 are controlled by a stereo fader, sporting only a balance control, two bus assign buttons, and a very limited 2-band EQ. The mono sends go to two master pots. The stereo returns each have a stereo master pot with two bus assign buttons. The monitor section has some features. Besides a monitor volume (which also controls the front panel headphone jack), this nice piece of work allows a choice of monitoring all or some of channels 1/2, 3/4, stereo, or cue (fed by four individual pots coming directly from the MiniDisc, just like the big guys!). The master fader is the same size as the channel faders, although it is also the same color.
If you're into fancy footwork, two jacks on the right side of the front panel are ready for foot pedals, each programmable to work several transport functions, including punch-ins. It doesn't matter what kind of pedals you have (open or closed); the unit will figure out what's connected to it when powering up.
The right side of the X4 is decidedly digital—from the standard Sony smoked window LCD display to the multiple function buttons. Grouped in four sections, there is no mistaking the transport controls, record enablers, locate functions, and editing/programming buttons. If you rest the heel of your hand just under the jog/shuttle wheel, all of the buttons, except the record enable buttons, are within easy reach. But, just a little stretch gets you record-ready. The transport controls sit under your thumb and include a "top" button which sends you to the beginning of the disk. A brightly-lit record button sits by itself under your index finger. Same finger works the locate section—mark, in, out, shift, and locators A-D (E-H when shifted).
In the editing/programming button group, you'll find the controls for repeat functions, time display (up, down, and musical bars), a rehearsal mode, auto punch-in, one-level undo/redo, enter, and exit. All editing and programming is menu-driven. Select the list of what you want to do, and spin the jog wheel. Touch the enter key with your choice displayed (exit and enter are closest to you, sitting under your middle and ring fingers).
In the programming department, vari-speed will go plus/minus 8%. However, it works in record as well as play—the combined 8% during record and 8% during playback adds up to 16%. Other user-defined parameters include: MIDI controls, on/off; MIDI device ID; MIDI Sync clock output, on/off; MIDI frames; footswitch one and two transport functions; pre-roll and post-roll seconds played (for rehearsal or auto punch-in/out); number of tracks being recorded (1, 2, or 4); volume adjust during rehearsal mode; display brightness; and undo/redo, enable/disable. It should be mentioned that undo only works if there is enough room on the disc to handle the backup material. When the unit realizes it doesn't have enough space to make undo available, it turns off the undo LED—still, one has to be careful not to make an edit, thinking undo is always going to be there.