To come to your question, Kali + Piano 2.1 vs TerraBerry
The Kali + Piano 2.1 combo has the advantage of being a dual-mono (or dual stereo) solution and you will be able to reuse the Kali in the future whenever Allo releases a new DAC that can take advantage of it (but cannot guarantee Allo will release a new one).
Sonically speaking, the Kali + Piano combo is indeed neutral, but less detailed than the TerraBerry.