My xrun woes have come in 3 flavors. The first seems solved, the second is a problematic mystery, and the third is a less critical conundrum. To get concrete:
- Right out of the box the 18i8 worked in terms of basic functionality. Off the bat I encountered xruns frequenty, one or two at a time, but I quickly came across these instructions (big thanks to raboof and whoever else helped compile that page - it was super helpful). Running through a number of those steps seems to have eliminated these frequent low-level xruns, sans 1 or 2 at startup.
- Where things get more problematic is that every once in a while I'll encounter a huge burst of xruns. Ardour will freeze, all the audio will cut off, and it'll start racking up xruns, ~10-50 per second. Sometimes it stops as abruptly as it starts after 100-300 xruns, but sometimes it just keeps climbing >10k until the audio engine disconnects. This happens even at seemingly reasonable sampling rates (<=48kHz) and buff sizes (256 samps). This is by far the most problematic of the three.
- If I configure Ardour to any sampling rate >48kHz or the lower buffer sizes (~<256 samps) I get the out of control xrun issue from above right off the bat. Never a moment of live audio, the xrun counter just shoots up from the start until the audio engine crashes. Nyquist limit discussions aside, this isn't a huge problem since I don't have so great a need to be recording at higher sampling rates. Since the 18i8 is said to go as high as 192kHz I'd like to at least understand what the limiting factor is here though.