For roughly 12-percent of $40,000, you can put together a music server that will rival CD playback systems costing as much as 50-percent of your $40,000 system ($20,000).
For less than $5,000, you can purchase a new comprehensive high-end music server (player/renderer, controller, server/source, WiFi router and cabling).
If digital music is your primary source for listening to music, your digital source is then a fundamental link in your system chain (not a place to skimp). Therefore, I think 10-percent, in your case, should be a minimum.