I've got audacious-1.4.5, audacious-plugins-1.4.4 and audacious-crossfade-0.3.3. If I select audacious-crossfade as audio output, audacious will refuse to reproduce anything with this message on the command line: MADPlug-Message: failed to open audio output: XMMS reverse compatibility output plugin audacious-1.3.2 + audacious-crossfade-0.3.2 used to work fine. [ebuild R ] media-sound/audacious-1.4.5 USE="chardet dbus libsamplerate nls" 0 kB [ebuild R ] media-plugins/audacious-plugins-1.4.4 USE="aac alsa chardet dbus flac mp3 musepack nls sdl sndfile sse2 timidity vorbis wma -adplug -arts -esd -gnome -jack -lirc -modplug -mtp -oss -pulseaudio -sid -tta -wavpack" 0 kB [ebuild R ] media-plugins/audacious-crossfade-0.3.13 USE="libsamplerate" 0 kB # emerge --info Portage 2.1.3.19 (default-linux/amd64/2007.0/desktop, gcc-4.1.2, glibc-2.6.1-r0, 2.6.24-gentoo x86_64) ================================================================= System uname: 2.6.24-gentoo x86_64 AMD Athlon(tm) 64 X2 Dual Core Processor 4600+ Timestamp of tree: Wed, 30 Jan 2008 06:16:01 +0000 app-shells/bash: 3.2_p17-r1 dev-java/java-config: 1.3.7, 2.0.33-r1 dev-lang/python: 2.4.4-r6 dev-python/pycrypto: 2.0.1-r6 sys-apps/baselayout: 1.12.10-r5 sys-apps/sandbox: 1.2.18.1-r2 sys-devel/autoconf: 2.13, 2.61-r1 sys-devel/automake: 1.4_p6, 1.5, 1.6.3, 1.7.9-r1, 1.8.5-r3, 1.9.6-r2, 1.10 sys-devel/binutils: 2.18-r1 sys-devel/gcc-config: 1.4.0-r4 sys-devel/libtool: 1.5.24 virtual/os-headers: 2.6.23-r2 ACCEPT_KEYWORDS="amd64" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-march=athlon64 -O2 -fomit-frame-pointer -pipe" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/kde/3.5/env /usr/kde/3.5/share/config /usr/kde/3.5/shutdown /usr/share/X11/xkb /usr/share/config" CONFIG_PROTECT_MASK="/etc/env.d /etc/env.d/java/ /etc/fonts/fonts.conf /etc/gconf /etc/php/apache2-php5/ext-active/ /etc/php/cgi-php5/ext-active/ /etc/php/cli-php5/ext-active/ /etc/revdep-rebuild /etc/terminfo /etc/texmf/web2c /etc/udev/rules.d" CXXFLAGS="-march=athlon64 -O2 -fomit-frame-pointer -pipe" DISTDIR="/usr/portage/distfiles" FEATURES="digest distlocks fixpackages metadata-transfer parallel-fetch sandbox sfperms strict unmerge-orphans userfetch userpriv usersandbox" GENTOO_MIRRORS="ftp://pandemonium.tiscali.de/pub/gentoo/ http://78.46.32.117/ ftp://ftp-stud.fht-esslingen.de/pub/Mirrors/gentoo/" LANG="it_IT.UTF-8" LC_ALL="it_IT.UTF-8" LINGUAS="it" MAKEOPTS="-j3" PKGDIR="/usr/portage/packages" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --delete-after --stats --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages --filter=H_**/files/digest-*" PORTAGE_TMPDIR="/var/tmp" PORTDIR="/usr/portage" PORTDIR_OVERLAY="/usr/local/portage /usr/portage/local/layman/sajinet" SYNC="rsync://rsync.namerica.gentoo.org/gentoo-portage" USE="3dnow X a52 aac acl acpi alsa amd64 bash-completion berkdb bitmap-fonts bluetooth bzip2 cairo cddb cdr cjk cli cracklib crypt cups curl dbus dri dts dv dvb dvd dvdr dvdread eds emboss encode evo exif fam ffmpeg firefox flac fortran ftp gdbm gif gimp gnutls gpm gstreamer gtk hal iconv ieee1394 ipv6 isdnlog java jpeg kdeenablefinal kdehiddenvisibility kerberos lcms ldap libnotify lm_sensors mad matroska midi mikmod mmx mng mp3 mpeg mudflap musepack mysql ncurses nls nptl nptlonly nsplugin offensive ogg opengl openmp pam pcre pdf perl php png ppds pppd python qt3 qt3support qt4 quicktime raw readline reflection samba sdl session sndfile speex spell spl sqlite sse sse2 ssl startup-notification svg tcl tcpd theora threads tiff tk truetype truetype-fonts type1-fonts unicode usb vcd vorbis wmf wxwindows x264 xine xml xorg xosd xpm xprint xsl xv xvid zlib" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" ELIBC="glibc" INPUT_DEVICES="keyboard mouse joystick wacom evdev" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="it" USERLAND="GNU" VIDEO_CARDS="vesa nvidia" Unset: CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LDFLAGS, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS
I've seen such errors with a broken config file or when the crossfade plugin can't open it's backend for some reason. I'd suggest backing up the audacious config and then retry with a totaly new config.
Fixed by doing rm -rf .config/audacious
