with a HDSP9652 the minimum for me is -p64 -n2 , and this is already very good low latency ;) with 32 i have : jackd -R -P89 -d alsa -d hw:DSP -p32 -n2 jackdmp 1.9.10 Copyright 2001-2005 Paul Davis and others. Copyright 2004-2013 Grame. jackdmp comes with ABSOLUTELY NO WARRANTY This is free software, and you are welcome to redistribute it under certain conditions; see the file COPYING for details no message buffer overruns no message buffer overruns no message buffer overruns JACK server starting in realtime mode with priority 89 creating alsa driver ... hw:DSP|hw:DSP|32|2|48000|0|0|nomon|swmeter|-|32bit configuring for 48000Hz, period = 32 frames (0.7 ms), buffer = 2 periods ALSA: final selected sample format for capture: 32bit integer little-endian ALSA: cannot set period size to 32 frames for capture ALSA: cannot configure capture channel Cannot initialize driver JackServer::Open failed with -1 Failed to open server Raphaël

On Mon, Jan 27, 2014 at 3:34 PM, Peter P. &lt;p8rpp(a)aol.com&gt; wrote: some specific revisions of the RME HDSP hardware can do <64 frames per period, but most cannot. 64 is the official lower limit (from RME).

On Mon, 2014-01-27 at 21:34 +0100, Peter P. wrote: Yesno, the HDSPe AIO theoretically can go that low, but in reality the card on Linux is a PITA. IOW I can start jackd with such a low latency, but I even get xruns at highest latencies. [rocketmouse@archlinux ~]$ jackd -dalsa -r44100 -p32 -n2 jackd 0.123.0 Copyright 2001-2009 Paul Davis, Stephane Letz, Jack O'Quinn, Torben Hohn and others. jackd comes with ABSOLUTELY NO WARRANTY This is free software, and you are welcome to redistribute it under certain conditions; see the file COPYING for details JACK compiled with System V SHM support. loading driver .. apparent rate = 44100 creating alsa driver ... hw:0|hw:0|32|2|44100|0|0|nomon|swmeter|-|32bit configuring for 44100Hz, period = 32 frames (0.7 ms), buffer = 2 periods ALSA: final selected sample format for capture: 32bit integer little-endian ALSA: use 512 periods for capture ALSA: final selected sample format for playback: 32bit integer little-endian ALSA: use 512 periods for playback ^Cjack main caught signal 2 no message buffer overruns [rocketmouse@archlinux ~]$ hdspmixer HDSPMixer 1.11 - Copyright (C) 2003 Thomas Charbonnel &lt;thomas(a)undata.org&gt; This program comes with ABSOLUTELY NO WARRANTY HDSPMixer is free software, see the file COPYING for details Looking for RME cards: Card 0: RME AIO S/N 0x579bcc at 0xfddf0000, irq 18