What are the specific differences between the circuits of the KGGS and current Stax amps? A lot of people are shooting from the hip, but I would be very interested in the substantive differences between the various designs.
I found that my Concerto ran out of gas with the HE-500's. Certainly good to a point, but not optimum. Channel Islands VHP-1/VAC-1 has more grunt, but still not ideal. So much more grip and dynamic headroom with my Opera Audio Consonance (two EL84's and one 12AU7). Although touted as "easier to drive", these need extra juice to sound their best.
Look for older DAC's with the now-gone Ultra Analog 20 bit chips. Enlightened Audio Designs DSP-9000, Resolution Audio Quantum and others. While lacking the ultimate detail of the best current DAC's, it just does not get any smoother than this. You can get the once- expensive gear at great deals today and they still more than hold their own.
My bad. I am in the USA and I have read that the USA version lacks both features -- I could very well be misinformed, or the USA version may be different. Regarding the lack of an SD card, it was reported that 25GB on Dropbox would be free for one year, certainly lending credence to the no-SD report.