it's not nessecarily nessecary. if you are recording live to the cd player it would definitely be a good idea, if you're recording from tape or a daw you'd still probably want to use a limiter across the mix but you can get by without it as long as you put your recorder in record-ready and let your mix play all the way through while watching the meter on your cd-r to make sure you don't clip your levels to disc. as far as that behringer piece goes, it looks like it's primarily a mic pre. so that's not really what you want. look for a compressor/limiter and remember that a comp with the ratio set to 10:1 or hirer is really considered to be limiting anyway.