I have a 6 gal Dewalt compressor and need to increase the CFM for a one off project.  I can borrow a 6 gal Rigid compressor.  Both compressors are rated at 2.6 SCFM @ 90psi and both compressors have the standard 2 female output ports. 
Amazon sells a male to male connector, www.amazon.com/Coupling-Connect-Adapter-...-1126923309038&psc=1 . 

I’m thinking of using this coupler, and the hose from compressor 1 to connect the 2 tanks together.  Then I can use the hose from compressor 2 plugged into the 2nd outlet port to power my tool. 
I realize that connecting the male to male to a hose will allow free flow of air, so I’ll need to connect the male end of the hose first. 
Are there any other problems with this setup? 
 
Thanks
 
Ron James

Well this wasn't a very smart statement:
"I realize that connecting the male to male to a hose will allow free flow of air, so I’ll need to connect the male end of the hose first. "
Of course, once the male to male coupler is attached to a hose, that hose has a male at both ends, so will allow free flow whatever end is plugged in first.  So I'll ensure both compressors are depressurized and turned off before connecting.  

Hi Ron,
The problem that you will have is on the control side of the setup. Whichever of the two compressors senses the low pressure first will start up to satisfy the demand. The second compressor will never sense a low pressure situation. This situation is termed "hijacking" and is common with heating and AC systems as well. The solution is to have both compressors controlled by a common air pressure switch so that both will start simultaneously on a low pressure activation. This video describes a solution:
hackaday.com/2016/07/12/parallel-compressors-for-sandblasting/
Good Luck !!!

Hi Valzan,
Thanks for your response. Very interesting video.  I hadn’t considered the current draw.  Since this is a one-off spray painting project, I’m hoping not to have to get into the
expense and complications of delays, relays etc. 
Regarding “hijacking”, a single compressor cannot keep up with the spraying demand.  I’m spraying at 30psi, and when the compressor kicks in, if I continue to spray, the tank
pressure keeps dropping and won’t build up again until I stop spraying.  I’m assuming that, with two compressors, the initial cut-in will take a little longer since I’ve effectively doubled the tank size, but when the 1st one kicks in, the pressure in both tanks will continue to drop, and the 2nd tank will kick in.  Would this not happen in my case, or am I missing something? 
As far a current draw is concerned, I can certainly put each compressor on a different 15A circuit.  The compressors specify cut-in pressures as “approximately 130PSI” so I’m hoping
they won’t both cut in within a short time of each other.  We’ll see. My workshop has its own sub-panel, so if I do trip the panel, at least the house won’t get tripped as well. Does this make sense? 
Thanks again or your thoughts.
Ron