I have a few suggestions, as I've been there done that and It stinks. I'm a huge cat lover and my cats before my children were my life. If you can believe it when I would find the pee I would just cry b/c I didn't know what to do. Here is what I used to do to cover everything.
If they there is usually a reason...Medical, which is the best and easiest. Have you taken him to the vet to see if he has a urinary infection? Very common in male cats. If they pee right in front of you that is usually the case. My male cats gets one of these every couple of years and he pees so I can see him and now I know right away he is sick.
Behavior - tough one - Once a cat pees he might always pee. If there is a change in situation they might pee to let you know they don't like it and want a change. New house - Could there have been a cat that lived there before him? Male cats are ver territoral. Are you gone more? he might be saying I don't like to be home alone. I know this sounds stupid but they are crazy creatures and want things their way. Are you sure it's the little one and not the older one?
I had a cat that peed on clothes every time I left them out or in a basket. I had a cat that like to pee in duffle bags, back packs. Every time my step kids would come over or my hansband would leave his clothes around, my cat would pee. It was terrible I was contantly picking up things to smell them. Before bed I had to make sure all backpaks were put where the cat wouldn't get to them.
Try getting another litter box, if you have 2 kids you should have 3 boxes. 1 cat one box but once you add multiple cats they say you should have one more box then cats.
Behavior meds - This is a stretch, but I was desperate and loved my cats dearly. I put my one cat of kitty prozac. However, that didn't work either. Sad ending I ended up just putting my one cat down b/c anything my husband , boyfirned then would set down, she would pee on it and it didn't matter where it was, couch, floor, sink, bed.
I had another cat that had the same problem once we moved, she never adjusted to the new house and dog and we got rid of her. Some cats just need a new home. They do not like change.
I only have 1 cat now and it's nice and sometimes I still find pee, but I have a nose for it now and it's not that often, maybe twice a year.
As for the smell, I have tried all products on the market and nothing can rid of the smell of cat urine. The best thing I ever used was Pinesol and poured in right onto the spot and let it soak for a few days.
It's been six months since I down a cat and I'm ready for another one but not sure Im ready for problems again.
Best of luck!!!!!