Digital amplifier fans, NAD C298 Purifi Eigentakt

I did look the Topping up based on a comment you've made previously. Pretty cool, but a little lite in the wattage department. 

I would highly suggest the same, honestly with class D amps I have never been a big fan.  I have never gotten to deep into all the modules so I dont want to use a few comparisons to generalize the whole thing.

The fact is you are dipping your feet, so I think that topping is a great way to go.  Even with the additional cables you will need it's totally worth it, and according to what most people say it doesn't have that class D sound that most people do not like.

Lastly to that, you must remember when it comes to power you need massive amounts to make a difference.  I am not an audio expert, but just touching on the subject.  If you had a 100 watts to get double the volume you need 1000 watts, it's a 10 fold scale.  

In addition to that, you must realize your amplifier is honestly only really using so much power at a given time.  It's far less than what you think, so if you already got a 100 watts turned up to max volume and that's not loud enough for you than going 300 watts would give you about a 30% increase in potential sound and 500 watts would give you a 50% increase.

Now that may not sound loud to you, but if youre getting a 100 db out the speaker and now you got 130 youre probably going to def on prolong periods of that.  This is just a rounded hypothetical situation to help you further grasp the concept.

PSAudio M700 mono blocks just over 3K. 350 watts @ 8 ohm, 700 watts @ 4 ohm. 

Here you go. https://www.peachtreeaudio.com/products/gan400

Though you'd be better off looking at Cherry amps and Orchard Audio amps.

To be clear, the 'D' of class D does not mean 'digital'. All class D amplifiers are analog; if not, its not a class D amp.