The pioneer has both coax and optical SPDIF output - i'm not sure if you have a preference, but if you want to use it as the ADC and record to a computer, you need to be able to get SPDIF into your computer.
The cheapest way is a simple SPDIF to USB adapter, something like this:
Armed with the right cable, and with software like Audacity, and with the Pioneer configured to route to the SPDIF output, you'll be able to record into your computer directly. The quality of the interface and the software to capture it will make no difference, since the signal is digital, and all of the potential problems will be added by the pioneer which you seem to be happy with.
Personally i'd get an audio interface with analog input as well as spdif, and compare the two. You'll find that for line level signals (assuming you have an existing preamp performing phono preamp duties) that there will be no audible differences, so it will allow you to ditch the pioneer at some point. Of course it's up to you to decide though, but that's just my opinion.
If you want to do some fancier editing of the recordings, noise reduction during quiet passages/between tracks, click/pop removal, you should look at demos of Izotope RX as an audio editor. The basic version (RX Elements) will do all you need, and there is a 10 day demo or something like that to try it out and see whether you can improve your recordings. Even something as basic as normalising levels will give you benefits on replay.
RX 10 is the award-winning audio cleanup software trusted by top post production engineers to quickly remove background noise and restore damaged audio.
www.izotope.com
It's the industry standard for good reason, and just about every field recording you've heard has been through it (or Reaper, but i'd not recommend that as it's a bit hard to get your head around by comparison).