Phono Stage, Cartridge, DeGritter...which one first?

Just FYI - my current system is a Rega P6 w/ upgraded Groovetracer platter & sub-platter & a Hana SL cart paired with an EAT Petit Glo phono stage.  It's all sounding pretty good but i've recently wondered if a new cart would take it to another level - then I thought about how clean my vinyl was...and so on.  I have clean power with Audience Adept conditioner, so I should be good there.

Vibrato makes a nice affordable RC although the Degritter has caught my eye and ear. 

If you were considering any of these changes, which one would make the most immediate improvement without narrowing it down to a specific phono stage or cartridge.

In this case you have narrowed the question down to where it cannot be answered. This is audio, not philosophy. 

If you're going to clean records, the Walker Enzyme 4 Step is the best, period. But not as huge an improvement as a better phono stage, or cartridge. Unless.... it all depends on which ones and how much, see?

Ahhh.  I understand your point.
Since the Degritter is around $3K, I guess my question would be - in my system listed above, any suggestions on specific improvements staying in that price range? Or go for the US cleaner?

Most of the work in cleaning records is in getting them out, moving them around, and putting them back away again. The actual cleaning is only a part of the process. And yet most guys for some reason focus in on this one thing and feel it is worth spending thousands to have this one box that all it does is what you can do yourself with a brush for $3.  

The thing about cleaning records, it is all about getting every last trace off. So you use a machine, the last thing it does is wipe the record with the same brush that has been used on a hundred records. In other words it smears the same crud around, only thinner, less of it. Unless you wash and rinse the vacuum tube between records, which no one ever does. 

So if you are going to buy a machine you either pay twice what you're talking for one that does it right, or you do without, or you do like me and only use something like the VPI to suck off the final rinse. Because by then the records are all pristine, so the vacuum bristles stay pristine. No one does this, I doubt you will either. I just like to put things out there because I find people do pick up on these things. 

Use this approach, buy the Walker Enzyme, maybe a cheap used VPI, and have money left over for something that will make a much greater difference, a good phono stage like the Decware ZP3. Recommending phono stages just got a whole lot easier because the best one under $10k the Herron at only $3k, they are all gone. Pretty sure. You might get Keith to sell you the last one. But it is probably gone. He was down to 2 last week. Anyway, the ZP3 is what you want. You can get it and all your cleaning goop easily under $3k. With maybe money left over for a nice high output Soundsmith cartridge. Now you are talking killer combo, all for only about $3k.