Build quality. Not reliable. SQ and SPL isn't really impressive either. Since you said "subs", remember that one good sub is better than two cheap ones, consider your total budget and look into getting one sub that'll perform similarly or better than the two cheap ones. Most common thing I'd see in my shop is someone thinking they "need" two 10s or 12s in a sealed box, when really one better one (ported OR sealed) would do a better job than both of the others, with less power at that.