[quote name='WHUFC BASS' post='946231' date='Sep 5 2010, 03:15 PM']Bugger - I found out yesterday my combo only takes 4ohm extension cabs.[/quote]
It its a Trace combo, which going by your other post, I guess it is, then it will take a 8 ohm ext cab, therefore giving the minimum load of 4 ohms, which is what your reading on the back of your combo.
The 4 ohm is minimum load, not impedance of any cab you wish to connect. The 4x10 will be fine.
Neil