It seems every bass forum I read has a thread or post about reliability problems with a GK head. I know about certain quality control issues a few years ago, but from the reading I've done online, some of those reliability issues apparently still exist. While I love the GK sound and am still looking to acquire a 400RB or 700RB used, the reliability of my Hartkes (I've owned three) has made an indelible impression. For my purposes, the combination of price and power offered by Hartke can't be beaten, as anything else in that price range is severely underpowered.