Hold your horses!!! Let me build and test and make sure the circuit works, do the FFT to prove the THD is same as the last one before you spend money. They are NOT on sale, they both been around like forever, so there is no advantage of buying it first. That's said, The chassis is definitely big enough, according to the dimension, the heatsink is at least as big if not bigger than my chassis. I bought the exact same transformer also. The chassis and the transformer can definitely do the job. I can spare two blank pcb, I put in SMD components on 4 pcb, two for you and two for Dan, it's a lot of work to build two extra as I do production line building 10 boards at a time. There are a lot of SMD components as the whole input and voltage gain section are SMD other than the transistors. I just do this for you two because I afraid SMD might be hard for people that never do it before and I am good at it.