I've installed a myriad of systems into cabinets and IME, you will need to get a couple of whisper type fans to exhaust the heat for any type of tube power amp. You will need one fan to exhaust the heat from the top of the cabinet. If you cut out a hole to match the chosen fan size (I prefer 4" muffin type fans) as high as possible on the back of the cabinet, as close to the amp as possible that would be best. The second fan needs to be as low as possible and mounted so that it pushes cool air into the cabinet.
If you buy 12V DC fans and a power supply that is adjustable from 6 to 12 VDC you will be able to control just how fast the fans run. In this way you will be able to fine tune between amount of air flow and fan noise. When looking at the fans you want the lowest dbu per CFM. I typically had no trouble keeping the fan noise below the noise floor in the room.
Or you can look at some cooling specialists like Active Thermal Management. (no affiliation)
BTW, proper cooling will greatly increase the amp life/reliability as well as spare the cabinet from damage.
If you buy 12V DC fans and a power supply that is adjustable from 6 to 12 VDC you will be able to control just how fast the fans run. In this way you will be able to fine tune between amount of air flow and fan noise. When looking at the fans you want the lowest dbu per CFM. I typically had no trouble keeping the fan noise below the noise floor in the room.
Or you can look at some cooling specialists like Active Thermal Management. (no affiliation)
BTW, proper cooling will greatly increase the amp life/reliability as well as spare the cabinet from damage.