I'm starting to feel responsible for more upheaval than may be necessary. Let me start by saying that I am not expert in Sonar and audio settings. I never had trouble before, but started having issues with 8.5 and then X1. My issues are distortion on trcks at low gain settings and a delay when arming tracks, not signal delay, delay from the time I click the button to when it is highlighted. This is both the Record and Input Echo buttons. My Fireface 800 has firmware 2.77, driver 3.034. I have a Supermicro motherboard with 2 dual core Xeon 5160 procs (3GHz), 8GB RAM, 3Gb/s SATA drives, GeForce X1300 dual monitor video, Ti chipset Firewie (I use 1394b). I run SONAR X1b (the latest patch) on Windows 7 x64. I have had the distortion problem occur with only one track recording with no effects loaded. I usually have no other programs running when I record. These problems have been intermittent, however, and since they began I have done my research and been much more careful in setting up SONAR. I have had less trouble, but I sometimes still get the arming delay and "crackling" distortion, which to me is digital distortion. The problems occur more frequently when I have put a drum track (usually Session Drummer) or other soft synth in before recording audio. I almost always record 24 bit, 44.1 and buffer size 64 samples. Sonar has an enable read and enable write to cache option which I have experimented with to no effect. I have seen other threads on Cakewalk and RME with similar problems and I believe they are slowly being addressed. X1's b patch seemed to make the frequency of problems diminish. I have seen a claim on RME's board that a new driver is coming because of a known issue with Win7.
All I have done at this point is to be very careful with audio settings, ASIO is still better than WDM but settings must be made first in the FF 800 and the set to match in the SONAR project. I know Sonar has been playing with enabling changing sampling rate on the fly but I don't wish to pretend I know what the causes of these issues are. I wish I could remember where I saw some of the info I have given here, like the new FF driver, but I don't. Maybe someone from RME can jump in here and tell us if they know of any issues and if a new driver is indeed coming.
At this point, I am still able to usually get things working nicely, but sometimes I get distortion at low levels and load and sometimes have to wait a few seconds for a track to arm. I also Audacity and haven't had these problems, but I use that mainly to learn about the code behind this technology and I just compiled ASIO support with Audacity last week, so the sample size of use is very small. I will search for the other threads with info on this and post them here.