@Fosi Audio
It would be nice if Fosi Audio create an ecosystem of reference gears around the V3 amplifier using the same enclosure.
The next step would be a reference DAC.
This DAC would have the RCA output at the same place as the RCA input of the V3 amplifier.
This way, Fosi could sell as accessory a special rigid U-shaped RCA "cable" with just the right size to connect the output of the DAC to the input of the V3 amplifier when the amplifier is sitting on top of the DAC.
In the same way, if the DAC use the same voltage range as the V3 amplifier, we could reuse the expensive power brick (and it would reduce e-waste and we could spend more on the quality of the DAC itself) of the amplifier, plug it in the DAC power input. The DAC would have a relay controlled power output where we could connect the power input of the amplifier using a rigid U-shaped "cable".
These very short cables would unclutter the back of the DAC and amplifier.
When we turn on the DAC, it would turn on the power of the amplifier, and when we turn off the DAC, it would mute the output and turn off the power of the amplifier.
To please those who want to buy multiple DAC/amplifier pairs in a multi-channel setup, an HDMI/SPDIF (like the HD951B) switcher (with HDMI 2.1 out pass-through but no DAC) with SPDIF output (3 or 4 SPDIF outputs) would allow to control these multiple pairs of the DAC/amplifiers. It does not need to include any media decoding as the bluray player can do the decoding and send multi-channel PCM on the HDMI link.
A way to set the delays, to manage the LFE channel and a 12 bands equalizer on each channel. The TI TAS3103 could do the job for the delays and the equalizer. It can even manage the volume. So there is no need to program a DSP. From what I can see in the datasheet, we could use it to manage the LFE channel too. This device should not be very expensive to manufacture.
The device should have trigger outputs to turn on/off the DAC/amplifier pairs and a remote control to set the volume and turn on/off.
As input and outputs, it should have 4 HDMI 2.1 inputs, 1 HDMI 2.1 output with ARC, 2 or 3 spdif input, 1 USB input (for USB DAC), 1 Bluetooth input, 4 SPDIF outputs, the same enclosure as the V3 amplifier.
The Bluetooth should be disconnected when not selected on the switcher. To keep the front plate simple, and as we set the equalizer only once, a RS232 port (using a TRS socket to keep this small) could be used to change the inputs, set every parameters of the switcher and especialy the equalizer, set the delays, the LFE parameters.
This HDMI/SPDIF switcher would be like a digital "preamp".
Later, Fosi could create a reference ADC which could connect to one of the SPDIF input of the controller/switcher.
If Fosi could sell empty V3 enclosures, it would be nice for those who want to create some DIY audio gears so that the look will match the V3.
Doing this, Fosi would create the first system which could evolve from stereo, to 2.1, 4.0, 5.1 or 7.1 just by buying more DAC/amplifiers. It would be a modular AVR.