ok firstly I'm a guitarist & I use a Vox AC30 (combo amp) so I have no clue about bass gear... anyway on Friday night, while setting up for a gig, our bass player's amp fried. Now it's the 2nd time it's happened, all he did was turn it on. he's sent it off for repairs but he said he might have to buy a new head since his is starting to get unreliable. However we're not sure what amp he needs to get (in terms of wattage etc). he doesn't know about ohms & watts so he's not sure what he needs to pump his speakers. Currently, he runs a 4x10" 600 Watt 8ohm and a 15" 600 Watt 8ohm, at the same time, with his current amp. he said he 'bridges' his 2 speakers together. We can't work out though exactly what this means. Is the amp actually running at 1200 Watts, 4ohms? or 1200 Watts 8 ohms? or 600 Watts 8 ohms? or 300 watts 8 ohms? or some other possibility? We want to buy a replacement amp that's going to do the job, but can't see many for sale that are more than 750 watts.