Aria ... not sure why you say I liked that it seemed to be saying it will act as a CD player with stereo sound. It seems that you may have a misconception here. As far as I know, all DVD players also play CDs (although the reverse is not true). So the fact that the DMP-BDT310 plays CDs as well as DVDs is nothing special or unique.
Also not sure why you say there doesnt appear to be much out there in cyberspace about it referring to the DMP-BDT310. I googled DMP-BDT310 and review and that search returns lots of user reviews (overwhelmingly positive) as well as a several professional reviews (overwhelmingly positive).
I have no firsthand experience with the DMP-BDT310, but based on the information on the Internet, my impression is that youve purchased an excellent blu-ray disc player for the money. Having said that, I would be stunned if the CD audio quality from the $175 DMP-BDT310 would equal the CD audio quality that a dedicated CD player or a universal disc player would provide.
Given the objectives youve indicated, I think you have two basic options either of which seems reasonable to me: (1) keep the DMP-BDT310 and supplement it with a dedicated CD player or (2) return the DMP-BDT310 and replace it with a universal disc player.
Assuming you want to buy new, then for option 1 depending on your budget, take a look at the Marantz CD-5004 ($350 list), or the Marantz CD-6004 ($500 list), or the Marantz SACD/CD player ($1000 list). For a new dedicated CD player under $1000, I think Marantz is very hard to beat but there are competing products from a handful of other good brands (such as Cambridge Audio and NAD to name two).
On the other hand, if you explore option 2, again assuming you want to buy new and depending on your budget, take a look at the Marantz UD5005 ($600 list), or the Marantz (UD7006 (list $1000), or the Oppo products (BDP-93 at $500 list or BDP-95 at $1000 list). There is also the Marantz UD8004 which originally listed at $2300 but is now available for $1150 as a closeout from musicdirect.com. For a new universal player under $1200, I think either Marantz or Oppo are very hard to beat, but again, there are competing products from a handful of other good brands (such as Cambridge Audio and NAD).