Another possible solution to increase contrast with Azo and Agfa WA: yesterday I was printing a negative in WA 1:7, and the print was sharp and overall scene contrast about right, but murky flat in the darker tones. The negative was HP5+, and the scene was recorded in flat light. I made a tray of WA 1:4, and this increased the snappiness of the print to where I felt good about it.