I've just moved from RHES3 and JReceiver to Gentoo and Ampache, using Paul Noffke's tRio with my Rio Receivers. I wasn't successful getting the current beta (Ampache-3.3.2-Beta2) working w. my Rio Receivers, so I downgraded to an earlier Ampache version (following your lead). My current working configuration:

Sun's J2SE 1.4.2.10-r2
Ampache-3.3.1.4
Roger Lipscombe's ssdp server
Jon Hodgson's AmpacheRecever
Current versions of dhcp, mysql, nfs

I had been using tRio w. JReceiver, but using the default trio.xml "arm" configuration, I haven't been able to get the Rio Receivers to find the server. I hope to see updates of AmpacheReceiver and tRio, with support for newer Ampache releases. I hope.