Congratulations! This is a fun opportunity. My take on this is that you are the most eligible candidate I have ever seen to go to an Audio Show. That is the only way you can see and hear a broad range of equipment without visiting a dozen or more showrooms. AXPONA (Chicago) happens April 12th through the 14th and they are giving a discount to early ticket buyers. I recommend going for the Gold Pass where you get access to a special lounge where you can rest and meet other well heeled audiophiles. I met my bestie audio buddy at the 2018 AXPONA and I ended up buying my beloved Thiel speakers from him.
I hate to tell you this but $100K is really not that much money when it comes to buying a new audio system. You could blow that on cables and power conditioning. You will see dozens of speakers that will cost most or all of your upgrade budget so you will have to be careful and strategic in getting the most for your buck.
I'm also going to make a few general gear recommendations based on my direct experience. I'm going to assume that you will have a pretty good idea about your room before you start buying new gear.
1. Focus on the speakers first. If you find a pair of speakers that you really like then you can decide on the amplification. Your current integrated amp is no slouch. However, if you fall in love with a pair of high sensitivity horn speakers then you would likely want to go with a lower wattage amp (tubes probably) that would be a good match for them. Conversely, if you decide on a pair of low sensitivity speakers with a difficult impedance curve then you will want a beefy amp to drive them.
2. Regarding digital gear, I have a KI Ruby SACD player, Berkeley Reference 2 MQA DAC, a Tubadour IV DAC, and a Jay's audio CD3 MK3 transport. I'm going to be honest and tell you that there isn't a lot of difference between the Jay's/Berkeley combo and the KI Ruby. I think most audiophiles would have difficulty identifying them in a blind test. If I were in your position I would focus on the speakers and amplification and keep your Marantz player unless you really desire a separate transport and DAC. BTW, I absolutely love my Jay's Audio transport and Berkeley DAC - they are beautiful pieces of gear and a joy to operate. I don't care if they don't blow away my KI Ruby in sound quality. They are fun to own.
3. Once you have become familiar with what's available you will be in a much better position to explore the option of buying used gear. This is the golden age for high end used audio and you can make your budget go a lot farther. There are so may choices that it takes some diligence but it's worth the reward.
I am 68, retired, and in the position that I could spend a fair bit of cash upgrading my system. I am running Thiel CS6 speakers, Krell KSA 300S amp, and a KRC-2 preamp. My core system is late 90's vintage; about 25 years old. I've been to three audio shows and I have come to the conclusion that it's going to cost me a whopping expenditure to better my system. Most of the systems I have heard sound fine but they aren't better than what I have. In several cases I have heard six-figure systems that clearly weren't as good as mine. I've heard several where the cables and power conditioners cost more than my entire system and they didn't impress me. A few have stood out, particularly MBL 101 E MKII speakers, but they are $80K. I could afford them if I really wanted them but I just can't justify spending the money.
As one geezer to another - have fun and don't be in a hurry. The process can be a lot of fun.