I only really need 1 channel at a time, as I record instruments or vocals individually, using the same Heritage audio pre-amp, connected to the adi-2, or a midi device.

Main reason I'm going HDSPe is for total mix's ability to route the audio back without going into the PC, mainly for vocal monitoring, but also monitoring in general.  I use ableton live suite and need to play the tracks from my DAW while also recording back into it.  I need to hear my voice in close to real time, so I can add tonal subtleties and nuances, and so far without total mix, the adi-2 and ableton through usb has not provided sufficient monitoring latency.

I believe an HDSPe card using totalmix fx can output audio from the DAW, while simultaneously routing the input back out in one output channel, without the input needing to go into the DAW.  The DSP will route that input back to the output channel directly on the card, allowing me to monitor the input at very low latency.  Essentially just the AD/DA and DSP latency will be present, not the DAW's processing latency.  Am I correct in that belief?

I have a midi device that I've been using through usb, but a midi input directly to the card could be an advantage?  If you believe so, I'd like to hear the reason for that.  I honestly don't know much about midi, except for that I'm able to track drums adequately with the device I have.  Come to think of it, I actually have another piano (88 key - keyboard) that only has a midi and analog out, so 2 midi's could be an advantage.

I'm planning on using AES for audio in/out connection with adi-2 and the HDSPe card. 

I'm a little fuzzy on the particulars of clocking.  If I go with the AIO or RayDat, then I could use adat for clocking.  Is that even needed in this setup or will one AES in/out connection also maintain clocking between the two devices, if they are the only two involved?  If clocking is necessary, then that will eliminate the AES card paired with the adi-2, correct?

The AES, besides being ~$300 more, doesn't appear to come with any breakout cables.  So I will need to buy that seperately, correct?  Just out of curiosity, I'm not sure I understand the pricing on this card.  It seems less versatile with essentially the same capabilities, but I suppose it's marketed for a large studio with many AES sources.  Which kind of explains the price in a way.

The RayDat appears to come with an AES breakout cable as well as a midi breakout cable, and has the benefit(need clarification) of being able to use adat for clocking, if needed.  This is beginning to feel like the best option right now.  Confirmation of the included breakouts, clocking, and HDSPe solving my dilemma will help in this decision

The AIO pro looks appealing, simply because it meets my requirements, appears to come with AES and MIDI breakout cables,  and has the the option of monitoring directly from the pcie card (headphone output) and not needing to output back to the adi-2, as well as you never know when additional AD/DA converters may come in handy for some random experimental workflows.  The only downside I see to the AIO pro, is that since I have 2 midi devices, I can only use one at a time.  That's not a deal breaker at all, just a miner inconvenience, as I mainly try to track a songs instrumental part in one session and can just change the plug at the start of the session.  It would be nice to have the ability to "quick play" though.

Any thoughts and/or guidance on this purchase will be greatly appreciated.  I wish I could've order this earlier as I'm off work for the next week, but hopefully it comes in by Wednessday or Thursday if there is an option for expedited shipping.  Thank you in advance.