[quote name='elliswasp' post='753650' date='Feb 22 2010, 12:03 PM']if your amp is rated at 1000w at 4ohms then you cant put two 4ohm cabs threw it if you do you will run the very serious risk of blowing your amp up. your choices are simple either change your cabs/speakers for two 8ohms cabs rated at anything up to 500w per cab personally i would have them at about 350-400 for the sake of head room or run the single cab and keep the volume down far enough that the cab isnt complaining about it.[/quote]
I don't think this is quite right. According to the manual, the LGs are 2 x 500 Watt into 4 Ohms, not 1000W into a single 4 Ohm load. What the OP probably needs is either a pair of 500W-ish 4 Ohm cabs, or two 350W-ish 8 ohm cabs. I suspect you wouldn't really notice the difference in overall volume between running each side at 4 or 8 ohm.
When I had a technical question about a piece of Ashdown gear, I emailed the support line and got an answer back the same day. I suggest that rather than guess, or spend a load of money on something you don't need, it might be worth doing the same.