So I got a rockford fosgate 500 watt 2 channel amp and 3 subs from a friend. Instructions say that it is 4 ohms stable when bridged. The subs are in parallel and together have a resistance of 1.33333... ohms, which is close enough for me for the 2 ohm stability when not bridged. Aside from getting another amp or just plugging into 1 channel, what are my options?