We have kind of adjusted our house to Rocky,I suspect that the others too have sprayed on occasion..though.
No more carpeting in the house,bed-room door is closed in the day-time,we don't leave anything laying around that could be a marking spot.
They still have lots of room to fool around in.
I have 2 Feli-Way diffusers,in the rooms they are the most,I have been buying Natures Miracle,but got a recipe for home-made stuff,I think Sugarcatmom gave it to 14+ and I am going to try that,much cheaper than Natures Miracles.
I am surprised your leather-couch smells like cat-pee,usually leather is very washable,we have leather too,but spraying rather than peeing is mostly done on vertical surfaces.
After cleaning with NM,did you clean with a leather-cleaner?
Before you do anything drastic,make sure he does not have UTI,my Rocky has caused me all kinds of problems,but it's something I have to live with,I love him,I got him from a barn-cat momma as a baby and he's here to stay no matter what.