I don't agree. I use Roland CM-30 monitor with built-in mixer. I use several inputs - one for POD, one for PC (to play guitar lesson DVDs or YouTube videos), and one for iPad (to play along with a backing track). I have a drum machine plugged into POD's CD-IN as a metronome. Sure I could manage with fewer inputs, or use POD's CD-IN for all external sounds, but with a mixer it is much more convenient. If your processor has no CD-IN (e.g. AmpliFi/Firehawk, or a cheap Digitech RP90), then small mixer is a MUST. I used to have a small Behringer and it worked perfectly until I bought CM-30, which has a mixer built-in, so I sold Behringer to save some space on the table.