Thank You For Succinct Answer
I don't see the point of using an external DAC unless you have a purely 2-channel system ...I'd much rather spend the money on room treatments or hookers.
I don't know about whether I'd spend money on either room treatments or hookers before I'd spend money on DAC, although the hookers idea has some promise.
Usually when I look stuff up on forums, I get a mixed bag that confuses me further, which was not the case when I went to this thread. I am a longtime Mac user who must obtain a PC for work-related reasons. For a while, I have been considering setting up a separate computer as a music server, rather than using my Macbook Pro for that purpose, and having to pull it in and out of my system. So, when I discovered I needed to get a computer anyway, I decided to Google regarding PC-based music servers. Most of the info is either too simple (how to use iTunes) or way over my budget ($3000 dedicated servers, etc.). When I kept coming up, on audiophile sites, to comments about going out to a DAC, I started wondering why I would want to go out to DAC when my Onkyo 807 had pretty good DACs. My question really was, "How much would I improve my midrange system with a DAC that is at the appropriate ($500ish) price point?" It seems pretty clear from the comments here, which answer that very question, that a DAC would be superfluous in my case. I thank all who responded here for answering my question in advance.
I would welcome comments from anyone on my plan to get a really cheap (but media-friendly, with HDMI output, etc.) e-Machines PC and go out from it via a Creative X-fi external sound card into my 807.