It's interesting that both start distorting more at 6-7k. I imagine that having 1/10th the distortion is not a chocolate-strawberry sort of difference, though I remember reading that the ear is surprisingly tolerant of THD below 1%.
On another thread I was asked about SET vs Volt+D. In my experience SET amps resolve more detail at low levels but at moderate levels and above there's little advantage. The Volt+D is more neutral than my SET amps but with less warmth.
Probably my question right? I mentioned it in that thread but what is my Volt+ putting out as far as power with their 19v power supply? 20 watts per channel? What does the Volt+D putting out with the same 19v power supply? If you already answer this question I apologize, I just can't seem to find it.
You'd have to account for the voltage drop across the capacitance multiplier (if a NPN transistor was used for the CM - i dont think they used a NPN transistor), the voltage drop is just under a 1v so that leaves the chip with around 18v.
From the datasheet you're looking at 18w @ 1% THD+N (into an 8 ohm load).
https://ipfs.io/ipfs/QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco/wiki/Bridge-tied_load.html
Parallel bridged tied load PBTL produced more voltage with a given power supply input voltage, but it doesn't produce more current. It's not exactly a free lunch, because you're also cutting damping factor in half. It's not that big an advantage with 8 ohm speakers, which I think is one of the reasons pbtl is used in car audio a lot (4ohm drivers).
Subjectively, the Volt+d does put out more power than the Volt+. I've never measured it though.
Thanks for the information. So that approximate calculation of yours is for the Volt+ or the Volt+D? Or is it roughly the same output for both? And my speakers are 12ohm 97db ZU Audios. How does that factor into the equation?