I voted for the reasonably priced NC252MP amp because I think it would sell the best. I currently use a miniDSP SHD as preamplifier and wouldn't mind upgrading my old power amplifiers to something new, but don't want to spend too much. I think the Buckeye amps are ugly.
Personally I would be more interested in a modern preamp or integrated amp though. I own the SHD because it has almost everything I want from a preamp. I have always liked integrated amps with pre-out/main-in connections so that a processor can be inserted. This allows use of crossovers, EQ, and the addition of subwoofers in the analog or digital domain. You can add a DSP with the latest ARC to this type of integrated amp rather than having to buy a whole new amp. The downside is that there is an ADC/DAC stage in the signal path and analog preamp circuitry degrading the signal.
For this reason my ideal device would be digitally based. I want all of the traditional preamp functionality done in the digital domain. Volume control, balance, tone controls, input switching and mute (soft fade), variable loudness and RIAA EQ (like RME), other cool phono preamp features (like puffin) all done digitally. There would be balanced and unbalanced analog inputs and outputs connected directly to high quality ADC and DAC circuits. There would also be lots of digital inputs, 2 Coaxial SPDIF, 2 Toslink SPDIF, AES-EBU, USB, HDMI. No need for streaming or Bluetooth built in IMO since those things become obsolete. I would rather buy the latest stand alone streamer. And since everything is being done digitally, there needs to be digital outputs, Coax, Toslink, and AES-EBU. This way the preamp can be used with modern DSP active speakers or stand alone DSPs without unnecessary ADC/DAC processing. It could also be used with a power amplifier with digital input such as you have proposed. I would of course use a DSP and it would be very nice to have a digital pre-out/main-in so the preamp's internal DAC can be used. Other useful features like delayable 12V trigger, input renaming, input hiding, auto-on, sleep, etc.. could be integrated with everything being digitally controlled. Would need to be able to update the firmware via USB in case new features or bug fixes come out. There could be a preamp version of this design and an integrated amp with a Hypex added of course.