6.2.1 / FW15 .... yes, just call me 'dinosaur'.

I left it at these versions as it has run flawlessly and several people swore that they sounded better than the versions that followed soon after. There was talk on various forums (inc. AC and SlimDevices) about the change in the volume scale etc and about potential fixes. Eventually, the code was patched in an attempt to resolve the issue and improve sound quality again. However, occasionally I scan the forums and even e-mail certain people, to see whether the original people who complained about the drop in quality believe that it is now back to where it was. So far, I have seen nothing conclusive on the forums or via e-mail to say that anyone has rigorously A/B'd the old and new versions and found them to sound the same. As it is still working fine, and it isn't possible to flick a switch back and forth to A/B/A them, I have simply left it alone.
I am probably about to move SlimServer from a dedicated P4 2ghz PC to my main Core 2 Duo 2.66ghz PC on it's own 500gb SATA2 disk, so perhaps I will update the SlimServer software then (and swap speaker cable connections around to maintain phase with the newer versions). SlimServer has such low CPU utilisation when running (a few per cent) that I see no benefit in maintaining a dedicated PC (with associated fan noise, windows updates etc etc) for it. The new (external) SATA2 HDD is connected via eSATA but also has USB2 so I can quickly move my music library across to my wife's laptop if there was ever a PC crash.