Must admit, did have me a little worried.I do not think that is what was meant at all. There is allot of placebo effect in this hobby and purists will always find a reason that something is not good enough. What it all comes down to is this. Most TOTL daps do not have a true line out and you will almost always be double amping. I think what Whitigir is really saying, is that from a purist perspective, this is not ideal. However, this does not mean that the M8 and C9 are a bad match, what is meant is that no double amping period is ideal, no matter which dap you use. The C9 is definitely a step up from the direct out of the M8 from what I percieve. In transistor mode, it adds balls, and weight to what is already there. In tube mode it adds some tube mojo and sweetness to the sound. I find it a clear step up from the M8 sound alone. Do I wish the M8 had a true line out, sure, but that is very rare.
Planning to wait to try the M8 with the C9 for a week or so and see what other people find works best, which gain setting, how much volume, 3.5 or 4.4, and than try.
Got plenty to connect and compare with the Lotoo and L&P players meanwhile.
At the moment the M8 is on bed side use with Elysium, my audio pajamas.