Odd Question... Speaker Output to an Attenuator?

[DetroitBlues]

My Marshall amp has multiple speaker outputs.  

If using the internal driver, could I hook up an attenuator to one of the other outputs so I can use its direct out for a PA?

Would that work? 

[Millennium Maestro]

I use (2) palmer PDI-09 boxes, record both guitar players live direct. you simply plug the amp output into it, run the speaker cable from the box to the cab. The Palmer has an XLR out to PA/Mixer
 

https://www.toursupply.com/product-p/pdi09.htm