Hello @redjr redjr,…
Glad to hear you found a Tone2 MK 
KHADAS SHOP vs AMAZON: Personally, I prefer to deal directly with Khadas, who has already been very accommodating in the past with some of my orders. The Tone2 MK is currently $116 on the Khadas shop
On the other hand, on Amazon, in the event of a problem, it is Amazon that handles the return, your choice may not be bad either …
W10/W11: I am also on W10 and no W11 yet so it is not possible for me to test the drivers to confirm the problem you are talking about. You can try to contact a Khadas Team technician directly by PM, again they have always been there to listen to me when I encountered problems.
ROON: I don’t use ROON, for the moment I still use my old one (DIY Case tuned Housing VIM2 + VTV + TONE-BOARD) with SPOTIFY or TIDAL in 320Kbps, it’s more than sufficient considering the acoustics of the rooms in which I listen to music
SERVIIO: If I had to install a stream server, I think I would turn to SERVIIO, it will be more than sufficient for me given the use I will make of it, plus it exists on Linux, Windows, Mac, QNAP and SYNOLOGY, 3 more reasons out of the 5 to guide me than SERVIIO.
TONE2 MK = TONE2 Pro: Perhaps, especially since we can read on (https://www.khadas.com/tone2) in the paragraph “Versatile Expansion” apart from the fact that we can power the TONE2 MK through the VIN port, the following:
“…, and OEM clients will have more options such as customized MQA decoding functions.”
What do you think of this sentence anyway? …
TONE2Pro and TONE2 MK FIRMWARES:
On the other hand, I don’t think that the firmwares are compatible, because the TONE2 Pro firmware does not allow the GPIO to be used as input!
That of TONE2 and TONE2 MK (see paragraph “input selection” of the TONE2, TONE2 MK and TONE2 Pro manuals).
Due to lack of time, I didn’t dig deeper…