As a fellow Resolution Audio afficionado, (I own the Resolution Audio Opus 21, btw), and a fairly recent returnee to the land of vinyl, (about 3 years ago now), I can offer you my opinions.
First, the Opus 21 is a great cdp. (Although, it is not quite the equal of the very best cdp's, notably the Audio Aero Capitole II, it comes quite close. But then again it costs about one-third the cost of the Capitole II, so for a bang for the buck aspect, it is almost unbeatable. However, the sound from vinyl is better still.
Second, it is not cheap to get better than Opus 21 cd sound, IMHO. I would guess it will take somewhere in the $2,000-3,000 range. Also, as AlbertPorter says, get something that is relatively plug and play. (This will eliminate most of the fiddling that DoudDeacon is referring to, so you can sit back and enjoy the music.)
I would recommend buying a "lightly" used turntable and arm, and something easy to setup, like a Rega P3, or better yet, something like a VPI scout, or a Basis 1400 (I started with the Basis myself. I recommend used, because if you don't like the hassles of vinyl, and let's face it-some don't, you can get out for almost no money lost.) I do recommend getting a new cartridge though, to avoid the possible problem of buying a damaged cartridge, and having to install it yourself. Plus, by buying a new cartridge, you can take the table, (and arm, if not already mounted to the TT), to your local dealer and have him mount the cartridge for you, thus avoiding the biggest hassle and pitfalls of setting up a proper analog system. (Again, this is what I did, and it made my life so much easier.)
Third, the biggest factor in going to vinyl is CLEANING the vinyl. This is a necessary requirement, and there really is no getting around it. Either be prepared to spend a lot of time cleaning records by hand (not really fun), or bite the bullet and get a cheap used record cleaning machine like a Nitty Gritty, or a Record Doctor, to help you clean/vacuum the records. (If you can afford the VPI units, they are better built, and a little easier to use, as you clean the record on the platter, as opposed to cleaning it on a separate table and then vacuuming it dry.) I went with a used Nitty Gritty 1.0 myself, (Yeah, I'm cheap!) and have no regrets. It works just fine, despite being one of the cheaper RCMs available.
Fourth, don't forget that in addition to the turntable, tone arm, cartridge and cleaning supplies, that you will need a phono preamp. Don't cheap out here! Spend the bucks and get a decent phono preamp, (Yeah, used of course!) Something like an Ear or an ARC work just fine and you can really hear the difference between the cheaper preamps and the quality preamps. (I started with an ARC PH-3, and it worked fine. I eventually went solid state, as I discovered that I really don't like the sound of tube rushing, but that is my personal taste. Most people barely hear it, so I recommend going with a tubed phono preamp first, and then if you don't like it, go with something else. Besides, the good solid state phono preamps seem to cost more than the good tube phono preamps, IMHO anyway.)
Well, good luck and don't be afraid to ask questions!