Which is proven better, laminate flooring with attached pad, or separate pad?

Some laminate floors come with a pre-attached underpad, making installation even quicker and easier. Laminate floors without a pre-attached underpad often require that an underpad be laid down prior to installation of the laminate floor to provide a level of cushion and sound absorption. Additionally, if the laminate floor is being installed on or below grade, or in an area subject to moisture, a separate thin plastic underlayment will need to be laid down prior to installation of the laminate floor to provide a moisture barrier. This needs to be done whether the laminate floor has a pre-attached underpad or not.

Actually the main thing is the pads, what is the use of laminate flooring with cheap quality pads, there is not any big difference between attached and separate, also make sure to use moisture barrier if you are installing over concrete.

Agree with Liam, high quality laminate flooring installed with low quality pads is total waste of money.