Allan: mine's the older 9now obsolete) ASI1600MM-C. The buffer is there to help reduce slow download issues (amp glow) for USB 2 users. I download over USB3. (Still get amp glow, but it is calibrated out with the darks).
Re the darks/flats, yeah, I can see no lines, except the ones I pointed out in the amp glow, which are at a different orientation and I think even fuirther down in the small scale noise.
Re bias ... I currently don't use bias frames (per Colin). But can try (per Greg) and see if that would help.
There's still the point that these lines are suspiciously running north-south. I don't believe in coincidences!
