The OT transformers are rated at 30watts down to something ridiculous like 5hz. In theory they could do a lot more at normal musical frequencies. In the end, the power supply will limit the maximum power. Well, that and my ears lol. While I expect to be able to get something like 30 watts from GU50, KT88 and the like. In reality I really only need a handful of watts And so will never need that much. On the other hand, maybe now I’ll finally have enough power to get a pair of LS3/5A monitors with their 83db sensitivity…