Vinyl System Upgrade Path Recommendations

I’d go with the Nagaoka MP110 then see where you’re at. That will probably be enough. If not, check back.

The Audio-Technica VM540ML at around $240 made a world of difference with my vintage Technics SL-1700mk2 that I recently restored. The micro-line contact nude mount stylus has class-leading wear rating that doubles most elliptical profiles, while bringing the music to life on a whole new level. 

@noromance @stereo5 @kommanderkurt - thanks for the advice guys! I'll take a look at the Ortofon and Nagaoka stuff. 

Does anyone else have experience with the Apt Holman Preamp? The improvement I got from the built-in photo stage over the one in my Eico was great but the mid tones (vocals especially) still seem muddy. I'm thinking it might be worth trying an external phono stage to see of there is a difference. Maybe it's better to start a new thread on that topic specificly. 

I also have a Pioneer PL-530 table. Bought it in the 70's new and haven't had the choice or finances to upgrade to something "much" better. Besides whatever treatments and cleaning you do to your records there are a couple of things you should consider about the Pioneer.....
First...have you investigated whether the tonearm support may have cracked due to age? This is a common problem for this table.
Is your current cartridge set up correctly? That is, other than using the crude overhang gauge that came with the table and other mounting parameters. When I first bought the table I used the supplied AT cartridge and was satisfied with the performance for a long time. I have tried a few different cartridges over the years with different results. Whatever cartridge you decide on is your choice. Tryouts for those is mostly limited.
One thing to remember if you buy a new cartridge is to set the correct tracking weight in accordance to the specified value.....This is a direct drive turntable. The most sensible thing to do is to set all the weight values to zero, set the tonearm so it is level, and then dial in the tracking weight. This is correct except for one step.....the auto mechanism must be eliminated to perform this correctly. There is an online manual that explains how to do that.
My Pioneer currently uses a Grado Gold cartridge. I feed it into a Graham Slee phono stage. I am happy with the sound. Your Pioneer is a good table. Sure, there are many more out there that perform better and with more expensive cartridges. But, it is a good table. Stay with it if you're happy.

@jrpnde - thanks for the notes! That's awesome that you've owned your PL350 since new! I did see some notes about the weak tonearm before picking mine up so I checked and it's all good. The table was serviced by a local shop (Austin Stereo) before I snagged it but probably worth double checking the cart set up. I mean overall the system sounds good, I'm just looking for great, on a budget. 

Have you tried other phono stages? How would you describe the sound of the Grahm Slee?