Some more stuff from the Seven String forum.
PS: I really don`t want to push these amps here cause I think, only a direct comparison will give the right answers in the end. But I guess it`s some good info to know.
Both amps will contain new transformers that are based around what the engineers at Peavey felt was "the best sounding example" of the original 5150 transformers. The transformer is actually the same one that is used in the Invective. They had multiple examples from the early runs in the shop, and based these transformers around the best sounding one, with a couple of tweaks to get it exactly where they wanted it. The new transformers will also be manufactured to a tighter tolerance, per Peavey.
Screen grid resistors have been updated to 700 ohms, as the original spec was meant to work best with the original Sylvania STR-387 power tubes that were standard for Peavey from the mid 80s until the early 5150 runns This change came with the 6534+ release years ago, though, and is not technically new to this amp. The power section layout was technically updated with all Peavey 6505, 6505+ and 6534+ models to accommodate EL34 power tubes with the proper pinout, but again, this happened with the release of the 6534+, not specific to these new amps.
Heater connections to the power tubes have been respec'd as well, as those were also prone to failure in older models. This is new to the 6505 1992 Original and 6505II
There were some other component quality upgrades made, but those details were not laid out for me.
The amps now have a detachable power chord.
The amps now have international voltage selection dials.