Need advice on how to dip a toe into digital

I have been using hi res files and computer since May 2010, I've experimented with quite a bit. Considering you own a PC, I agree with Gz3827 completely.... I might suggest Foobar 2000 instead of JRiver, JRiver is good, easier to use than Foobar, but once properly set up and updated to the latest software, Foobar sounds as good as JRiver.... If you don't mind spending the $50 or so, just get JRiver.
If you are not an apple head and you have enough hard drive, I'd use WAV files period, if space is a premium, then I'd look at FLAC. There are several under $500 USB DAC's that are very good...
The newest version of the Schiit BiFrost w/USB, one of the very latest Audio-Gd DAC's are excellent for the money.
Both have Asynchronous USB, at least 24/192 file capability and sound quite good for the budget.
I hope this helps,
Tim

Easy and inexpensive way to start is connect your computer to any line level input on you stereo using a stereo to dual mono RCA Y connector. I started that way and results were surprisingly good. General purpose computers are inherently noisy devices ie produce a lot of EM noise, so use a long Y connector so computer does not have to be close physically to pre-amp to connect. I've used a 12' Audioquest G-snake like this to very good effect initially before moving on to using Wifi enabled network players for a wireless digital rather than wired analog connection.

Dipping your toe won't get comparable sound quality to your current CD player or vinyl playback system.

Get the newer ARC CD9 with the built in digital inputs and match it to an Apple Mini or laptop using Pure Music or equivalent software. The downside is you won't have DSD playback.

As Grace Slick so eloquently stated, "either go away or go all the way in".

Gz... and others, thank you very much for your suggestions. I will read them a couple of times and see what I can do. Also, totally unaware of audiophile grade redbook. Where can I source such CDs and how do you know that it's audiophile grade? As I've posted elsewhere, on rare occasion I have some across some redbook CDs that are outstanding. My latest discovery is Michael Buble (Reprise).

Onhwy... excellent quote!! Btw, the newer ARC CD-9 retails for about $13K. Too steep a dive for now. I'd rather switch out my ARC VS-115 for the new ARC REF 150, the latter being a great match for my REF 5 SE. But that's ok. If you're really digitally crazy, ARC recently introduced the REF DAC for the bargain price of $16K.

Bifwynne To me, any CD that is not an SACD is a redbook CD. I don’t know if that is 100% technically correct, but that’s the way I think of it. When I referred to “audiophile redbook” I was thinking of CDs that are labeled with such monikers as Gold CD, HDCD, K2HD, XRCD, XRCD2, XRCD24, UltraHD, Ultradisc, and DXD. I believe all of these are PCM format which is indicative of redbook (as opposed to SACD which is DSD format). Playback of XRCD and the others I’ve mentioned does not require an SACD player; any CD player will do. Presumably CDs that carry these audiophile monikers are superior in sonics to mass market CDs because they are said to employ better mastering and/or manufacturing techniques. FIM (First Impression Music) immediately comes to mind as an example of a record label that specializes in producing such audiophile redbook CDs. The websites of online retailers Acoustic Sounds, Music Direct, and Elusive Disc are three that I know of which put a focus on audiophile redbook CDs. In my experience anything that I’ve heard which carries the FIM label is about as good as it gets on redbook CD. Unfortunately, the price is also about as high as it gets!