Luckily Steve is always forthcoming about being in the business, and of course he'll tell you that his product will help; how else would he stay in busniess?
I read through W4S's J River setup guide and they hit all the important spots. Your setup is solid, and I'm sure you'll get plenty of enjoyment from the DAC as-is. More to Steve's point: sometimes the "all-in-one" solution isn't the best. For PC audio this becomes especially true, given everything that happens from the moment you press Play on the file, to the moment it reaches the analog outputs of your DAC. I cuurently use a modified M2Tech Hiface that runs "off-grid" on battery power. You would not believe the improvements this made in my system. To each their own, and I'm never one to push people to buy more gear; I'm just telling you my findings.
Just remember: You can NEVER recreate the music that has been destroyed during the recording, downconversion, or complression process. You may hear a "difference" when upsampling, but you're not really improving the source material.
Since your hapiness is really all that should be important, I say upsample away, you're not hurting anything.
