Doesn't the 600 have angled sides... ie an angled top in horizontal ? I have enough trouble with things sliding off a flat-topped subwoofer -- you would need a case of blu-tac to keep things from sliding off a 600...

... but the bass would be awesome, which is all that really counts

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8