You have way too much hardware!
Just kidding --
Things to check:
Today a fellah was using too many plug-ins in WinAMP - more specifically, a crossfade plugin (under a DSP stacker maybe?) that was taking too long to do it's stuff... Check the CPU util on the source box.
The connection from the source/DSP to the DNAS -- local I assume? same PC maybe? -- if it's the same PC, use 127.0.0.1 in the DSP address... If the DNAS is on the same LAN, use the DNAS LAN IP -- Avoid the temptation to use the public WAN IP -- it allows the router NAT logic to get in your way -- The public IP works (with some routers), but is the worst of the "choices" you can make.
Verify your upload rate -- the ISP rating is not important, it's what you really get right now that means anything -- http://nyc.speakeasy.net/
-- try all sites -- use the worst one to determine what you really have available to you.
You also need to verify what is going on at the remote relay site -- while you may have all your ducks in a row, they may not. Proxies and other network noise may be in their way. Pings and tracerts are good tools when run on both ends.
The station is reporting drop outs ? Their listeners? The relay should visit your DNAS as a listener -- what do YOU see for the DNAS in your stats -- if the relay is underrunning the "feed" from your DNAS, you'll certainly see it in your /admin.cgi plain as day. Also pay attention to the buffer position -- a few K is fine, close to a Meg or two indicates a communication issue (and impending underrun) between you and the relay.