trailblazer no sound from rear door speakers

[gillette106]

I have a 2004 Chevy trailblazer. I got in to got o the store the other day and realized that my rear door speakers were not working. I checked fuses and none were blown. I have a line out splitter attatched to the rear speaker wires behind the stock radio for my subs. My subs are still pumping, so that tells me that the radio is putting out signal to those rear speaker wires, but still nothing from each of the rear doors. I am curious if there is a simpler way to fix this aside from taking the rear doors apart to check the speakers. is it possible the radio is shot? what are the chances that both door speakers blew at the same time?

Thanks for your time. Any help is appreciated.

[PaulD]

probably pretty good odds, OEM speakers are not all that great - they lasted 7 years