underlay 2in1 vs separate dpm?

[junglejim01]

i'm about to lay some laminate floor on concrete base which is a bit uneven and trying to decide if i need separate dpm or if i should go for the 2in1 stuff. Quick-step softboard says its suitable to accommodate unevenness but needs dpm is this the gist of it...2in1=thinner and better on even surfaces?
Thanks for any advice, also can anyone recommend brands?
ta

 

[junglejim01]

Anyone used this: http://www.diy.com/nav/decor/flooring/flooring-underlay/SELITac-5mm-Foam-Flooring-Underlay-12608623
cant find any reviews. Looks like the job but seems cheaper

 

[crazydaze]

So long as you use a DPM, the difference in levelling will be in the format/composition of the underlay itself, 4-6mm product either fibreboard or laminate/engineered roll underlay will be the best you can do without further floor prep.