The Samson PL1602 is a 2U size, 16 channel (8 stereo) rack mixer with 2 (left & right) aux sends and 4 (2 stereo) aux returns. It has EQ (bass & treble), volume, balance/pan controls per channel. The first two stereo channels can also be used for MONO microphone channels without phantom power. The first 6 (3 stereo) channels and the MAIN LEFT and RIGHT outputs have insert busses to connect to other outboard.
I decided to go for the Samson PL1602 after an extensive search for a good rack mixer with enough channels to support my rig. Finding one with both microphone and line inputs together with EQ and effects busses in a 1U unit was difficult, if not impossible. The PL1602 met my specifications up to the size. I wanted 1U, but ended up with a 2U.
I use the PL1602 to connect two microphones on the first 2 channels, the first VL70 to channel 5/6, the second VL70 to channel 7/8, the MAIN OUT of the Alesis S4+ to channel 9/10 and the AUX OUT of the Alesis S4+ to channel 11/12. This leaves the stereo channels 13/14 and 15/16 open for external synths or (electric/digital) piano's of other band members. The AUX send 1L goes to my Digitech Stusio S100 effects processor and back to the AUX return 1/2. The effects are only used for the microphones, since all the synths have onboard effects.