it could be a number of things that makes your cat pee on the couch homie. cats are super territorial and can be doing this to mark his territory even if he has been neutered.
do you have any other animals that live with you or close to you that live nearby? (that could be a big reason why he pees on the couch)
i suggest only using one litter box (if you just have the one cat) and keep it away from his food/water bowl. cat's don't like to poop where they eat!

true story though.
there are products that you can get to keep cats off of furniture but they tend to work on some cats and not all. it really depends on your cat.
please don't crate your kitty!

that will only make him go crazy and then you'll have bigger problems on your hand. also a night room would be a good idea if it was big enough but it wont solve the problem. he'll just pee on your couch during the day.
i would ask your vet and even your groomers what you can do about it.
