On Thu, 30 Mar 2017, Bill Purvis wrote: Yes and no. Now I can ask some questions :) Are all of the cards hard synced? (Do they use the same media clock?) Do they have to be accessable at the same time? Or is it good enough to switch audio cards on the fly without stopping jackd? How much do you care about quality? (is it ok if some of the audio is resampled?) Best quality = just one audio interface with a stable clock. Apparently Digidesign manufactured an audio interface with such a bad internal clock it actually sounded better with a master clock. next best quality = more than one interface synced with word clock with very short cables. next best quality = AVB networked audio interfaces lowest quality = resample to sync In all cases there are better and worse options. As I stated above even internal clocks can be bad. The Digidesign 192 interfaces are just one example (see http://pinknoisemag.com/pink-papers/pink-paper-002#aestheticrise ) resampling is very common in the broadcast industry where all the AES3 inputs can be set to resample (in the same way video frame storage is used to sync remote video sources). Can you hear the difference? I don't know. I personally think that if you are going to have more than one card used for output, resampling will not hurt. I would prefer to keep my inputs synced. Anyway zita-ajbridge will allow a second or third card to be added to jack. With or without resampling. ALSA will allow two cards known to be in sync (word clock used) to be used as one card. -- Len Ovens www.ovenwerks.net