Well, I am not a good reviewer .....
In my chain, with the Monica DAC in front of the Yamamoto, the sound of the GS1k is very smooth from bottom to top. Compared to the HF2 the bass goes deeper, the sound(head)space is much bigger. Every instrument is located at its place. But in opposite to the HF2 the whole presentation is more laid back. There is a welcome warmth coming from a slight emphasis of the top-bass to low-midth region but overall the sound is well balanced over the whole spectrum. The bottleneck of this more "neutral" character (with slight bass emphasis) is that the creme of the Yamamoto, the liquid midrange, is not highlighted as with the RS1. Female voices are nevertheless a pleasure to listen to. Instruments are sounding very natural. Listening to piano music I wish the bass impulses to be faster (even the modified D10 seems to be faster, but not to go as deep with the GS1k - it might be a problem of the USB Monica in the chain, too?).
Taking all together, while having some pleasure with the GS1k and the Yammy, in my sight it is not the ideal combination, best match.