I guess the answer to this question is, "正" or not is very personal. To me, I've got a full 石 setup, so, I would like to have another "taste". 膽 must give you totally different taste and mood vs 石. Most of the CHing said 前膽後石 is always be the best combination. Which will give you the best balance and get the most benefit out of the 2 types. So, will give it a try.
And as discussed with the Sales, which we know each other very well, did a quick calculation, if I get this, and later get a cheaper DAC, the quality must be better than I get the expensive DAC with volume control.