I have had this problem for a while. I enable crossfade in Lubuntu's Audacious, and a popup says the sample rates are not the same, so it can not crossfade the songs. So, I enable the sample rate converter plugin, and it doesn't seem to work. I still come up with the same popup box from before. This is getting annoying. I've tried all the different modes, and even switched from using Alsa, to PulseAudio, and back to Alsa. No such luck. Does anyone have any ideas on how to fix this?