Amp - preamp or integrated

Have you changed the tubes in the pre section? Very satisfying and worthwhile changes.
What is your front end? table, DAC, etc? Look there for upgrades.
Interconnects, speaker cables?
And the biggie ....room treatments.

Yes I own the Cronus Mag II it's quite excellent here.
I will never go back to separates. One of the biggest improvements I made in 5 years was the room treatments. GIK Acoustics.

The Vandies may be a little laid back wake them with the tube changes.
I owned these years ago and were very good.
Just my opinion of course.

First thing is keep in mind that there are integrated amps that are designed as separate amp and preamp within one cabinet. If you go with an integrated amp, put that high on your list. I’ve leveraged that with my two NAD integrated amps wired to bi-amp my speakers. Your choices of configuration are just as unlimited as with separate amp(s) and preamp. 

First, I estimate that my budget for new amp /pre amp or integrated will be around 5K after selling my Rogue Chronus Mag 2.  McIntosh would be out of range unless I get a good deal on used ones. 
My Rogue integrated although 4 yrs old, the tubes have low hrs. I barely put 10- 15 hrs per month. Short of 10k hrs they claim to last. Adding a subwoofer was brought up in this thread also. 

Preamp Audio-gd Master 1. About 2k shippment included. Someone compared it with some much more expensive Krell preamp saying the M1 blew it out of the water. Some others believe it can easily compete with preamps costing 3 to 4 times its price. Look for it on Internet. 

Class D Power Amp Nord Stereo SE (dual mono) with Rev D boards. About 2.5k shippment included. Someones compared it with amps costing 50k or more. Look for it on Internet. 

Hulgich Audio won the best sounding stand award in the Melbourne Hifi Show in 2017 and second place in 2018, with Nord amps and an Audio-gd DAC, competing against systems costing up to 500k. And the Nord amp used had Rev C boards, not the Rev D ones. Ive had both and Rev D is much better.

Do your research. You can have a 4.5k preamp-amp combination that can easily compete with multi thousands systems. You wont regret it. 

Im sorry, the Audio-gd Master 1 will cost you about 1.5k if you buy it from Audio-gd website directly. 
M1 + Nord = about 4k, a HiFi steal