What is my weak link?

I just upgraded to a Luxman SQ-30 tube integrated. My turntable is a Thorens TD 146 (auto stop/lift). Stock tonearm with Denon 110 HOMC. Speakers are Dynaco a25XL (recapped). I realize that the Thorens was entry level (in 1983 when I purchased). I think system sounds great, but, I have only old integrated to compare (Rotel don't recall the model). If I were to upgrade, should I start with TT or speakers? Or, keep what I have and use $ to buy more records? I know you guys hate these lame questions. But, I had to ask.
Or, keep what I have and use $ to buy more records?

In my Opinion, That is always the answer if you are a music fan and you have a limited budget. You already said you think the system sounds great. Don't muck it up. Listen and enjoy.....
As long as you're happy, stay with it. Make sure you have good supports for the turntable and speakers. Try solid core 12 gauge mains cable on the speakers and upgrade your interconnects if using basic stuff.
I haven't heard your luxman but i suspect it's pretty awesome. i believe it's phono stage has low output MC capabilities. You might mos def wanna experiment with a few LOMC carts. I also upgraded from rotel amp/pre to a tube based amp/pre. I have found the most dramatic improvements in my system were mostly at the front end. also i agree with noromance about cables (solid core) and good support/damping for your tt.
I suspect power cords will bring a smile, but try before you buy.
If it moves your soul, then dont change it. If I were pushed for an answer. I would change that DL-110 on the Thornes to one of the Grado wood body Prestige cartridges $350-$600 range...They sell both low and high output ones so you can match it to your phonostage,these are all moving Iron types. This IS the cartridge for the Thornes, so I would start there. Good Luck.
Re "weakest link": your system is actually pretty well-balanced, at a certain price point. There's a lot to be said for that. Leave it alone.
Your self.

I was a double stacked Advent 1970's kind of guy with an Onkyo integrated amp, Luxman TT, ShureV15 type IV cartridge.

Then, about five years ago we moved into a house with a good listening place, and I happened to hear some Maggie 1.2's and the rest was history.

Several thousand of dollars later, just once in a while, I ask myself if it was really worth it?

So...do not listen to other gear!

Buy more records!
Thanks for all the suggestions. I guess I will basically change nothing. I may experiment with cartridges. Lots of knowledgable folks on this site. Keep it up.
p.s. - i had a td 166 that was heavily damped with aluminum & vinyl damping sheets / heavy brass feet (mapleshade) . sounded better than a new $1800 modern tt. i lost a lot of money when i sold the new table! i have since realized that many new tables are just tweaked out/modded old designs. check it out - http://brooklynaudiophile.blogspot.com/
Have never heard the Dynaco 25XL but I assume the speakers are at least 30 years old? Even if speakers are the most flawed audio component, IMO loudspeakers have made the most advancement in sound quality over the last 30 years.