Finally upgrading my amp

Hegel H190. Good chance it’s going to be yours for $2500

https://www.usaudiomart.com/details/650031655-hegel-h190-integrated-amplifier-black-like-new/

Look at a Sugden A21 SE Pure class A amp, you will love it.

Agreed, your electronics could use a refresh. The Denon looks cool as a vintage piece, but you can get significant better performance. This can be had for $2,500 used as The Music Room deals. https://www.audiogon.com/listings/lisb8bi7-simaudio-moon-i-7-stereo-integrated-amplifier-56917-solid-state?refsource=hifishark It is high end kit. Looks really nice in two tone. There are less expensive solutions, just from my expience this is the good stuff. Unfortunately, no phone stage so not sure if it meets your needs. Llikely excelent more cost effective solutions, but it is great to do it once and do it right. Once you get the integrated sorted, I would stick with Marantz and save up for a decent DAC and then use the Marantz as a transport. PS Audio Directstream DAC are going for a super reasonable price. I see one listed for $1,150 just using as an example. Good DAC and the performance/$ is crazy good, as there were so many sold and folks are going to the MK2 and other solutions. There is an upgrade path with the APS nickle transformer mod can run with the best out there, but I’m getting ahead of myself. Sounds like a fun journey. Go slow, and enjoy the process. I like going used from quality well established sellers.  

Sounds like you are in for a fun journey.

I'll second a used Hegel integrated.  The highest up the chain you can afford.  Hard to beat IMO. But, I am biased, I own the H360.  If you can up your budget just a little.......

Check Hifishark, there are several available right now close to your budget. 

Good luck!

You could get used Peachtree Gan400 and the PreDac (preamp) used for around 2k and be done.