Newbie question - You mentioned in your wrap-up that you thought the output transformers were the reason for the low wattage, and talked about scaling up to the 15 watt model and seeing if it got you a few more watts. With 10 watts potential on the output transformers, why is final output not at least a little higher? My brain wants to jump to the conclusion that if you're not getting 10 watts out of a 10 watt transformer with adequate power from the PSU the issue must be a lack of gain or something else on the input side. Or is it just general inefficiency of the tubes, etc? If it's gain would expanding the design to a parallel output tube configuration help get more out of the OTs? Or is moving up to a larger transformer the only option for more power in this particular design? It would be awesome to see 5+ Wpc. Would scaling up either the number of tubes or the wattage of the OTs be pretty straightforward or would the overall architecture of the amp need to be upgraded? Thanks!