Its all going to depend on the temperaments of both dogs. I had a male and a female, then brought in my female GSD. My older female is very good tempered and has allowed all my finds into the home, but she is the boss and everyone knows it or figures it out. One time I took in two other females, the younger female of the two decided to push it and there was a minor fight that I was able to break up and no further incidents in the following 2 months. Your dog sounds like he's got the same temperament of my female GSD and she gets along great with my male golden...they are inseparable. Don't get me wrong, the GSD loves my older female, but the older one picks and chooses when she wants to play...most of the time she is off by herself(she is very independent) I think that you should be okay with another male, but just in case things change, are you guys opened to an even tempered female?
Misty- Samoyed Mix
Tannor- Golden Retriever CGC
Robyn- German Shepherd CGC
"A dog is the only thing on this earth that loves you
more than he loves himself."