The M-1 620's are active ((self-powered)) monitors. They've got balanced XLR and 1/4" inputs, a gain control knob, a bass density switch, as well as high, mid, low-boost switches, and an AC voltage select switch.
The M-1 620's have a very clear, solid output. They're not hyped in the high end, unlike some popular nearfield monitors. With the high-boost switched on they're a little to bright for my room, but in other rooms i'm sure it would come in handy. I keep the mid-boost switched off as well. The low-boost ((3dB)) switch I keep set at 56Hz. The M-1's reveal problems in the low end of a mix. They have a nice flat output and show your mixes for what they are, whether good or bad or great.
These monitors can really crank, and they sound good at higher levels. I keep them isolated from the stands using Auralex MoPads. They have fairly low self-noise, but I wish they had even less.
The M-1 620's are a very good value for the money.