I compared Fosi V3 and AIYIMA A07 and decided to keep a unit of AIYIMA A07 that I already have now.
Fosi V3 has better capacitors and a much better passive heatsink in a metal case with ventilation holes, but AIYIMA A07 has a volume knob that shows decibel levels and a separate power switch.
V3's volume knob doesn't show decibels. It is also a power switch. I can't keep it at a precise volume. Thus, it's difficult to precisely tune the gain structure of the entire audio system with V3's volume knob.
According to my calculations, if the analog volume knob is at -20dB or below, there is almost no difference in signal to noise ratio between lowering DAC volume and decreasing the volume at the analog volume knob. So, I just keep the volume knob on AIYIMA A07 at -30dB and adjust DAC volume and application volume.
It is a lot easier to adjust the gain structure if I keep the volume knob at a fixed position and adjust DAC volume and application volume.
However, Fosi V3 has a much better heatsink in a metal case with ventilation holes. For high power application, Fosi V3 is much better than AIYIMA A07.
With less than 200mW, AIYIMA A07 reached volume levels too loud for me because my speakers are close to me. If you actually need to push an amplifier beyond 500mW ~ 1W often, then Fosi V3 is a better choice because it can dissipate a lot more heat efficiently.
For now, buy AIYIMA A07 with LM4562 op amp because there are reports that some units of AIYIMA A07 come with fake NE5532 op amp which sounds bad. I would patiently wait for something like Fosi V3 with a separate power switch and a decent volume knob or no volume knob.