Hello Skyscraper,
I figured that I would put my two cents in on the SA-KI Ruby. I recently picked one up on Audiogon about a month ago, for only $ 2600.00. It took a long time to burn in; but I have been enjoying it ever since. I think that the best advantage is how it up-converts CD playback into a 11.2 Mghz DSD signal. I don't like to play the numbers game; but the SQ of this Marantz conversion is legit, being one hell of an impressive implementation. The SA-10 does the same; however, at a considerable higher cost. The sound-stage is wider, deeper, and instruments have a longer decay. I would say that the Ruby has the magic of leaving you thinking it has less detail; but leading to the full realization that the detail is still all there, only further back with more air and harmonic content. It is almost like everything has more room to breathe.
The real magic begins when using SACD Disks. Only now, with this Marantz 11.2 implementation, can I finally hear the advantage of DSD over CD. Natively, the differences were always hard for me to decipher. Kicking the SQ up another notch; the Ruby can convert multi-channel DSD Disks to a stereo down-mix, while still retaining a large percentage of the increased multi-channel sound-stage. The only thing that I have heard comparable was a MLP ( Meridian Lossless Packing ) DVD Audio 24/ 192 multi-channel disk, also down-mixed. The harmonic ambience could give analogue a close run for the money.
If I ever get bored ( Doubtful! ), I still have a sturdy and robust disk spinner with a digital output. I can still connect an R2R Dac, or any Dac I want. The Ruby still gives me various digital options that I might not have otherwise. Still, there is only one ( thrifty? ) way to get the Marantz 11.2 implementation. Anything in addition is only icing on the cake; but this 11.2 might be the whole cake, and eating it too. You might just forgo any other external Dac, and put your money into multi-channel SACD music compilations. Putting your money into music; instead of your equipment, is this audiophile heresy? I stand guilty as charged. Other options might be viable; but maybe I am just being a little greedy.