Despite a run in with gk over a burnt out driver, I had an rb 400, loved it, I now use an rb 1001 mk2 with 2 1x12 neos, have 2 mb 150s, an early one and a mk 3, one I use with an swr 1x10 and one with a glockenklang 1x12... I love the flat sound of gk, its true and the nuts, as for hartke, look for 'biscuit' on here he has an endorsement with them, hes nice guy too.