so I'm taking on the project of building a box for my alpine type r 12" subs and have run into a few problems in the past with building box so I'm really trying to limit the size of the box

setup:
-2 12" Alpine type R subs
-Hifonics bxi1208D wired to 1 ohm, suppose to be 1200rms but realistictly around 1000rms is more like it or a bit less

first question

-will a single box with 2 sealed compartments be louder then 2 individual boxes? I was kind of leaning towards the 2 individual boxes because it is much more convenient for me and i know it will fit, although i know a single box looks better

and my second question

-any tips for building boxes that are good for SPL but still decent for listening to? I'm looking into this currently but just wondering if there's any advice you have to share on this

thanks for the help its greatly appreciated