To prove my point, here are a few of Amirs graphs side by side (unfortunately, the old A07 review did not have multitone and two-tone):
The Douk is cleaner for all harmonics except HD3 at -92 dB which is not terrible but poor for PFFB. In fact, the A07 is better at about -94 dB.
We have a clear winner in the A07 for high frequency THD+N in the A07. Look at how even at 15 kHz, it stays below - 70 dB even out to 30 W. This rivals the champions of TPA325x PFFB amps, the PA5(II) and 3e A5!
Those 32 V power supplies are rare compared to the more common 36 or 38 V (I realize even 48 V are availeable but might lead to unhealthy idle heating). But it is interesting how the A07 squeezes out more power from the same voltage (77 vs. 59 W at 4R, 48 W vs. 33 w at 8R). Note how the Douk A5 significantly underperforms it own power specs at 8 and 4 R, while it admirably handles 2 R which is not even specified.
I wonder why it is behaving so poorly. Clearly, it is not a high resistance output coil or we would not have the near perfect load invariance (that is actually better then most PFFB amps). It can't be magnetic binding posts (I just received mine and checked).
And for good measure, here are some results by member UAN:
Wonder if there's a signal sensing auto-on/off function when used as a power amp (BP mode). There is no auto-ON/Off signal sensing feature for the amplifier, auto-ON/OFF is there only for screen display
www.audiosciencereview.com
Wonder if there's a signal sensing auto-on/off function when used as a power amp (BP mode). There is no auto-ON/Off signal sensing feature for the amplifier, auto-ON/OFF is there only for screen display
www.audiosciencereview.com
This is at 5 W (presumably 4 R) and seems to be in PA5 territory!