critique my setup -- weak link? best way to improve?

You will get WAY more bang for the buck with a $500 Bluesound Node and an $11/mth Qobuz subscription than any turntable/cart/phono stage upgrade at 4 - 5 X the price.

Spend the rest on upgrading your speakers. The used market will serve you well, just buy from someone with a lot of 100% favorable reviews here or on USAM.

Then maybe upgrade the pre-amp with all the money you saved not buying vinyl.

Cables later, lots of choices, buy used or from small direct to consumer sources like Frank at Signal Cable.

Just my 2 cents, and FWIW I started 6 years ago with a Pro-Ject Carbon Debut and look where I ended up - fortunately I’m still married, unlike this guy

I am sorry, the audio “source” is analogous to the OL of a pro football team? 

Sure it is, in football there is a place to start to improve the team, the offensive line is where I would start, again you can have Tom Brady....in his prime, won’t do you any good if the O line isn’t up to snuff, same with top running backs, won’t find a hole.

In audio...same thing where to start ? start with the source, some people say speakers which seems ok but think about it, do speakers make any sound, nope, they need to be hooked up to and amp via speaker wire, then preamp, then source.

The amp is more important than the speakers, preamp more than the amp, and guess what the source is the most important of all, if compromised there, the whole system is compromised . I mean would you put an original Sony CD player from the eighties thru an old 50 watt technics receiver into a pair of 10k speakers......you will get. a sound. I guarantee I could put together a system for FAR less and get a much BETTER sound.....all day.

One of my systems back then was a Linn LP12/Ittok/Black Koetsu cart/Mitch Cotter step up. into a NAD 3020 int amp into a pair of ADS 420 $350/pr speakers...I had them next to my Snell Type A large floor standing speakers, when I played the system for people they thought they were hearing the Snells, when I told them nope just the little book shelfs........man did jaws drop !