Thought the below might be of interest to some. The last is the best :-) Hardware and clients identical, octo 4GHz, test load is one yoshimi with jack_keyboard driving by way of a passthrough mididings. ---------------------------- Item one is vanilla distro jack2, run like this: jack_control start jack_control ds alsa jack_control dps device hw:SB jack_control dps rate 48000 jack_control dps nperiods 2 jack_control dps period 128 jack_control dps midi-driver seq jack_control dps inchannels 2 jack_control dps outchannels 2 jack_control eps realtime true jack_control eps realtime-priority 50 jack_control eps clock-source 1 The above is as low in reported latency I could go, 5.33ms, using every optimization I know of via the Arch wiki and realtimeconfigquickscan and other sources. Running load-less, it gives me usage ranging 0.9 through 1.4%, usually hanging in at 1.3%. With the test load, it tends to sit at 10% and rise with stress. A few xruns every once in a while are inevitable, even when the test load is delivering only silence. Nice tone quality. ----------------------------- Item two is jack1-git, compiled with Zita libraries engaged, run like this: nohup schedtool -R -p 50 -e /usr/bin/jackd -A SB -R -c h -X alsa_midi -d dummy -r 48000 -p 32 & Reported latency is 2ms. Load-less, usage rating is 1.3% through 29%, usually hanging in at 1.4% or so. With the test load, it sits at 31.2% at silence. No xruns. But no actual sound came out :-) ----------------------------- Item three is jack1-git, Zita libraries present but not used, run like this: nohup schedtool -R -p 50 -e /usr/bin/jackd -R -c h -X alsa_midi -d dummy -r 48000 -p 32 & nohup schedtool -R -p 50 -e /usr/local/bin/zita-j2a -d hw:SB 2ms reported latency. Loadless usage is 20%. With test load, 25-33% at silence. No xruns. Distorted sound. ------------------------------ Item four is jack2 vanilla distro, run like this: jack_control start jack_control ds dummy jack_control dps rate 48000 jack_control dps nperiods 2 jack_control dps period 32 jack_control dps inchannels 2 jack_control dps outchannels 2 jack_control eps realtime true jack_control eps realtime-priority 50 jack_control eps clock-source 1 schedtool -R -p 50 -e /usr/bin/a2jmidid schedtool -R -p 50 -e /usr/local/bin/zita-j2a -d hw:SB 2ms reported latency. Loadless usage 3.8 to 4.3%. With triple test load (three Yoshimis which is actually SOP for this rig), 4.5-5.5% at silence. No xruns. Wonderful sound, and no xruns with that triple load being pushed. Will be starting rigorous testing at lower latencies soon, but I have an instrument which has to sing first :-) Jonathan E. Brickman Ponderworthy Music | jeb(a)ponderworthy.com | (785)233-9977 | http://ponderworthy.com