Lo he probado con rosegarden en dos máquinas que tengo , con Debian Etch y Lenny , en ambos casos  rosegarden casca.Cuando desisntalo horgand-dssi vuelve a la normalidad.Te pego el error por si te vale (Etch) :


 supertux@debian-1:~$ PluginFactory::instance(dssi): creating new DSSIPluginFactory
LADSPAPluginFactory::discoverPlugins - discovering plugins; path is [/home/supertux/.dssi] [/usr/local/lib/dssi] [/usr/lib/dssi]
LADSPAPluginFactory::discoverPlugins - trace is Rosegarden 1.5.1 - AlsaDriver - alsa-lib version 1.0.13
JACK tmpdir identified as [/dev/shm]
Enhanced3DNow! detected
SSE2 detected
KCrash: Application 'rosegarden' crashing...

JackDriver::initialiseAudio - JACK sample rate = 44100Hz, buffer size = 512
JackDriver::initialiseAudio - creating disk thread
JackDriver::initialiseAudio - found 10 JACK physical outputs
JackDriver::initialiseAudio - connecting from "rosegarden:master out L" to "alsa_pcm:playback_1"
JackDriver::initialiseAudio - connecting from "rosegarden:master out R" to "alsa_pcm:playback_2"
JackDriver::initialiseAudio - found 12 JACK physical inputs
JackDriver::initialiseAudio - connecting from "alsa_pcm:capture_1" to "rosegarden:record in 1 L"
JackDriver::initialiseAudio - connecting from "alsa_pcm:capture_2" to "rosegarden:record in 1 R"
JackDriver::initialiseAudio - initialised JACK audio subsystem

  ALSA Client information:

    14,0 - (Midi Through, Midi Through Port-0)                  (DUPLEX) [ctype 2, ptype 655362, cap 99]
    16,0 - (TerraTec DMX6Fire, MIDI-Front DMX6fire 0)                   (DUPLEX) [ctype 2, ptype 589826, cap 127]
    16,32 - (TerraTec DMX6Fire, Wavetable DMX6fire 0)           (WRITE ONLY) [ctype 2, ptype 589826, cap 74]

CREATED OUTPUT PORT 3:out 1 - MIDI external device for device 0
Connecting my port 3 to 16:32 on initialisation
done
Creating device 0 in Play mode for connection 16:32 Wavetable DMX6fire 0 (write)
Default device name for this device is MIDI external device
CREATED OUTPUT PORT 4:out 2 - MIDI external device 2 for device 1
Connecting my port 4 to 16:0 on initialisation
done
Creating device 1 in Play mode for connection 16:0 MIDI-Front DMX6fire 0 (duplex)
Default device name for this device is MIDI external device 2
Creating device 2 in Record mode for connection 16:0 MIDI-Front DMX6fire 0 (duplex)
Default device name for this device is MIDI hardware input device
CREATED OUTPUT PORT 5:out 3 - MIDI output system device for device 3
done
Creating device 3 in Play mode for connection 14:0 Midi Through Port-0 (duplex) (not connecting)
Default device name for this device is MIDI output system device
Creating device 4 in Record mode for connection 14:0 Midi Through Port-0 (duplex) (not connecting)
Default device name for this device is MIDI input system device
AlsaDriver::setCurrentTimer((auto))
    Current timer set to "system timer" with timer checks
AlsaDriver::initialiseMidi -  initialised MIDI subsystem




  PD .- Una sugerencia para horgand "standalone" , cuando lo arranco , si tuve seleccionado jack como sistema de sonido y quiero arrancarlo con alsa , necesito primero:
 - iniciar jack ,
 - iniciar horgand,
 - cambiar las preferencias ,
 - volver a cerrar horgan y jack
 - reiniciar horgand,
     ¿sería posible que horgand se iniciara y que diese el mensaje de error , una vez iniciado, con la opción de configurarlo sobre la marcha? no se si me explico .
   Gracias por tu estupendo trabajo.