Help create my Mac Music Server

• I've just installed a PCI card from M-Audio (Audiophile 2496) that inputs and outputs 24/96 analog data & coax S/PDIF input/output . I have it in my Dual 1.42 GHz PowerPC G4 Deskside (dedicated to this application), running OS-10.5.7. As yet I haven't used it. I intend to insert 2 internal 1 GB drives in a RAID configuration - it will hold up to 4 internal drives (ATA/EIDE). My intention is to build up a HiDef digital library. I intend to transfer my thousands of records by sampling them at 24/96 from a very good vinyl playback system. I intend to sample the output from my $30,000 Audio Note DAC 5, rather than rip them from the CD - I'm hoping this will produce better sound thru the 24/96 DAC than I would get thru a cheaper CD-DAC when I sell my DAC 5. For CD quality (that I would get from ripping my CD's) - I plan on to output the data thru the S/PDIF output on the Audiophile 2496.
I don't know what music library management system to use. iTunes won't hold the 24/96 audio. I also plan to purchase all future music from HD Tracks (HDtracks.com) in 24/96 format (FLAC because of it's error correction capabilities for downloads & lossless compression on my HD). I don't know what s/w will convert the FLAC to 24/96 on the fly as I play the music. If I can't find such an on the fly converter, I may have to store them on my HD in the full 24/96 format, which will take up substantially more space.
I don't know for sure yet, but I think my 24/96 M-Audio card will also playback 24 bit/88 kHz as well as 44 & 48 kHz and iPod music. I may be able to come in on the S/PDIF input and go out the 24/96 and have it upsampled as part of the Audiophile 24/96. It may upsample from CD quality on my HD - all unknown as of today.
Any thoughts on any of the above would be appreciated.
Music library/playback server s/w - FLAC convertor - Audiophile 2496 capabilities - ... - all for a Mac - PC is not an option