Hi,
This is probably a bit premature, but since it is probably usable I should announce that an early version of my DSSI host is now available for keen alpha testers! The Linux binary and source can be found at:
http://www.puredata.org/Members/jb/
under dssi~.
On my machine, it supports Hexter, fluidsynth-dssi, xsynth, sineshaper, less_trivial_synth, and trivial_sampler.
It is currently Linux only, but an OS X version is very high on my priority list. This very much work in progress, and things like the creation arguments will probably change. Also, only a single instance of each plugin is possible at the moment.
Bug reports and suggestions are welcome, but please check that they are not listed near the top of dssi~.c before emailing me.
Enjoy!