Thank you coders :) now I can use Linux to make music :). Regarding to 'nobody does report success, just bugs are reported' I guess NO MIDI JITTER is worth a crossposting. $ uname -a Linux edubuntu 2.6.33.9-rt31 #1 SMP PREEMPT RT Tue Apr 26 15:05:31 CEST 2011 i686 GNU/Linux jackd 1.9.8 I guess svn 4290 or earlier Qtractor 0.4.8.69 svn 1978 Ardour2 1:2.8.11-1ubuntu1 a2jmidi_bridge 6-0ubuntu3 jackd --sync -Xalsarawmidi -dalsa -r48000 -p256 snd-hrtimer loaded and used as ALSA seq timer source, unfortunately there aren't enough timers to be used with JACK clients, when using the "-c" switch. With Ardour (synced to Qtractor by JACK transport) I recorded - Yoshimi, JACK MIDI - Hydrogen (as sample player only, not using it's pattern sequencer)and DSSI plugins hosted by Qtractor, ALSA MIDI - via PCI Envy24 MPU an Oberheim Matrix-1000, Yamaha DX7, Yamaha TG33 connected by a MIDI thru chain I didn't record all instruments at the same time, but one after the other and sync is perfect, no audible jitter. Unfortunately I couldn't use -Xalsarawmidi for recording MIDI events on MIDI tracks, because there's no bridge. FWIW, Ardours latency compensation is ok too. Ardour just isn't restoring the SMPTE offset, which isn't a big deal, because I don't use it now and manually setting it does work. My machine is a $ hwinfo --cpu Model: 15.107.2 "AMD Athlon(tm) X2 Dual Core Processor BE-2350" Clock: 2100 MHz $ hwinfo --memory Memory Size: 4 GB When building the kernel I set 'echo "CONFIG_HIGHMEM4G is not set" >> .config' and 'echo "CONFIG_HIGHMEM64G=y" >> .config' and btw. 'echo "CONFIG_MK8=y" >> .config' too. The distro is Edubuntu 10.10 Maverick 32-bit + Ubuntu Studio meta packages. Using the FLOSS nv driver for a NVIDIA GeForce 7200 GS on an ASUS M2A-VM HDMI motherboard. The two PCI sound cards are not used as one virtual sound card. Both are active, but I only did use one of the cards. I didn't use any USB device, but e.g. a PS/2 mouse and keyboard. PPPoE and screen saver were enabled, CPU frequency scaling was set to performance. Still one issue left. Any recommendations for a sound card with good audio qualitiy ;)? I guess I could spend around 700,- EUR and I need minimal 2 or better 4 analog IOs, mic pre amps etc. aren't needed, I'm using a mixing console. At the moment I 've got two TerraTec EWX 24/96 PCI cards, which cause a muddy bass sound. Thank you very much for the good work again, Ralf