to 1 - For recording it is recommended to use a recording interface with TotalMix FX. This gives more flexibility in routing and other things (loopback recording, etc) and the design of the recording interface is in a way, that you can have near-zero latency monitoring of e.g. Vocals while recording/listening to a backing track.
So at this point its unavoidable to have at least one recording interface plus the ports that additionally connected devices have. But this is not a waste, the ADI-2 Pro/DAC FS products can easily be integrated into such a solution, so that you have the additional benefits of an ADI-2 Pro/DAC. Perfect converter for your main monitors and phones with advanced features for a phones preamp. See my Blog article how to integrate an ADI-2 Pro: https://www.tonstudio-forum.de/blog/ind … our-Setup/

to 2 - This adds a few dB of SNR, for those who like to use it that way, but no real audible improvements. I would use the ADI-2 Pro FS R BE for other reasons:
- has two independend D/A converser, so that you can have different output levels for monitors and phones and use the key remapping feature to switch between monitors and phones with a safe slow ramp-up of volume when switching, so that there is enough time to adjust the level, if it should be too loud.
- has an analog input, you could also connect a microphone preamp to it
- has also digital outputs (ADAT, SPDIF, AES)
- has a sample rate converter if you need to connect other devices which can only give, but not read clock information. e.g. DAT with fix 48 kHz, but the rest of your equipment runs on a different sample rate
- has additional i/i ports, that are common in the studio (AES, ..)
- allows A/B headphone comparisons as it has two DACs for quick A/B switching
- more predefined routing possibilities on the device
- supports the usual Studio Levels

to 3 - Now I did not understand exactly how you mean that. I would connect the main monitor and phones to the ADI-2 DAC/Pro and let it do the D/A conversion, the ADI-2 * will probably have the better converters anyway. The ADI-2 DAC/Pro is digitally connected via ADAT to a RME Recording interface. The connection from PC via BBF Pro - ADAT - ADI-2 * is lossless. Furthermore it is probably safer for your ears if you don't connect monitors digitally, so that at 0dB level your ears don't fly away. This saves the purchase of a monitor controller. In the course of time you will find out that external D/A converters can (not must) be upgraded every now and then. If the D/A conversion is done in the monitor, then changing a complete speaker system (which might deliver the perfect sound for you) is probably more expensive on the one hand and unnecessary on the other.

to 4- By the way, in the use case of wanting to connect the monitors via AES, there are no reference levels. BBF Pro - ADAT - ADI-2 Pro - AES - Speaker.
And if the D/A conversion and volume control takes place in front of the speaker cabinet in the ADI-2 Pro/DAC, then you just take the reflevel that is quietest anyway and then control the volume down to a tolerable level. It would be ideal here if the monitors also had a volume control as for example with my Gaithain RL906D. In the meantime, I no longer use them digitally. There the volume poti is turned down completely and on the ADI-2 Pro I work with autoreflevel and volume settings in the range -10dB - -35dB or if I want background music on the PC workspace down to -40 or -50 dB. I then use dynamic loudness so that the signal does not flatten too much at low volume.

to 5 - to be able to offer a HiFi product at a more affordable price around €1000. The I/O is perfect for HiFi.
But in the Studio I definitively prefer the Pro model with two independend DACs with the possibility to switch between those.

I personally would do the following, just a proposal based on my personal experience:

1. would get a recording interface that matches your requirements
    The Excel in the Blog can support you when choosing such an interface
    https://www.tonstudio-forum.de/blog/ind … B-MADIfac/

2. get ADI-2 Pro FS R BE and connect it digitally/lossless via ADAT to RME recording interface with TotalMix FX

3. perform D/A conversion to monitors and phones on the ADI-2 Pro FS R BE.
   As it has two DACs you can switch much easier between Monitors and Phones at the device, for this ....

4. ... configure the ADI-2 Pro in the way I proposed in this article to be able to switch between monitors and phones
    https://www.tonstudio-forum.de/blog/ind … our-Setup/

5- Yoiu do not necessarily need to sell your ADI-2 DAC (if you have it already). Use the ADI-2 DAC e.g. in front of your HiFi, get an Oehlbach Optosel 4:1 MK II TOSLINK switcher, then you can connect different sources to the ADI-2 DAC FS and use this as "central instance for high quality D/A conversion" in front of your HiFi.

6- You could even think about connecting Recording and HiFi Area to make HiFi to "Monitor B". For this purpose it would be ideal
- if the distance between these two areas would not be more than 15-16m, so that you can still use a TOSLINK cable
- its required that your recording interface has either a 2nd ADAT or an AES output for this 2nd optical connection
Then you could make a connection from your recording interface to the 2nd ADI-2 DAC in front of your HiFi and make the HiFi to Monitor B or to use the PC as a bit perfect player for Audio. I have here a 15m TOSLINK cable between UFX+ and ADI-2 Pro FS R BE in front of my HiFi to the TOSLINK switcher, then 1m from TOSLINK Switcher to the ADI-2 Pro. So in total 16m. And this works still perfect up to 192 kHz.

If you still plan to connect the monitors via AES, you should also keep the following in mind:

Most monitors either do not have volume control or it is not active when you use a digital input on the speaker.
This means that things like
- power-on crackling or
- accidentally set 0dB
will cause your monitors to go straight to full power, which is not good for the monitors or your hearing.

You may also incur additional costs because an AES output is a stereo output. You would have to invest in an AES splitter, as is the case with my Gaithain RL906D, because there is no splitter on these monitors to loop the AES signal through to the second monitor. That would be then to all the disadvantages mentioned again €349 in additional costs for an AES splitter: https://www.thomann.de/de/mutec_mc_11_a … verter.htm

BTW, if you want to avoid powe-on crackling entirely, then have a look at my excel. All RME interfaces have power-on noise dampening on the phones ports, but only certain more expensive interfaces have it on all ports (802, UFX II, UFX+).
See also line 82 in my Excel: https://www.tonstudio-forum.de/index.ph … 0-08-xlsx/
So in that regards it is good to connect monitors and phones behind ADI-2 Pro, to isolate the potentially very loud monitors a bit ... compared to have direct digital connections to a very loud monitor system.

Or in other words, if you would combine e.g. BBF Pro FS with ADI-2 Pro FS R BE and connect monitors/phones behind ADI-2 Pro, then you have in total excellent D/A conversion quality, all the nice features of the ADI-2 Pro AND you should have solved issues in terms of power-on crackling because the ADI-2 Pro would dial-in the last saved volume during power-on.