How good can it get, really? - my stereo sounds amazing!

The Cronus is a nice sounding amp. I had the same amp with the kt-120 tubes and the only thing I did was to replace the preamp tubes, change to a 4 ohm load, and got a nice power cord, which makes a big difference in any system above the Best Buy 1 box units. I sold it because it wouldn’t control the bass drivers, too loose sounding.
since you are using 2 subs, this might not be a big deal. Also, since you have B&W speakers, you want a warm sounding amp.
The room and speaker positioning are probably the biggest areas you should do before thinking about better equipment. Once you get the room dialed in, then any tweak or improvement you do you will realize the full potential of your purchase.
BTW: cables can make a big difference especially if your equipment is of good quality

Power conditioner to lower noise floor is best upgrade for any mid-fi system, IMHO
Best value is AudioQuest Niagara 1200
about a grand .

Kinda reminds me of the Porsche 993 911 Turbo that I owned with 600HP/ 596 ft lbs torque and could do 200 mph all day, but it just wasn't fast enough for me ?! How much is too much and when do you stop?? I don't have FU money in my audio system but I couldn't get the smile off my face yesterday as I wallowed in music heaven

..and where done . Thanks for coming out everybody . 

Kinda the place I'm at now. I have a great (to me) system consisting of a Linn Klimax streamer, Burmester 077 two piece preamp, Burmester power conditioner, pair of Burmester 911 amps, and a pair of Wilson Alexx speakers. Looking at the Wilson XVX's now. That would cost me $240K after trade in for the Alexx's. Would they sound better? Almost certainly. But would they be worth the money? That's the dilemma! There will always be the next great component. When is enough enough??