I usually run Logic and my DM4800 with FW card on Yosemite, but earlier this week I loaded Sierra on an external drive and just for the heck of it installed the current drivers from the Tascam.com site. I haven't given it a thorough testing yet, but all of the basic I/O between the DM and Logic seems to be working fine with Sierra, exactly the same as with Yosemite. I'll be recording 10 tracks of drums this weekend. I guess we'll see then if it's working okay. I did get a disc too slow message once with just one track playing in logic, but the audio was running off of a Glyph drive(same drive as the Sierra OS). Despite being marketed as THE drive for recording audio, my 1TB Glyph is slower than any of my 4 internal drives and normally I do not use it for audio anymore. If I see anything odd, I'll post it.