I don't quite understand what you mean by 4K, is that what you will have to spend? Awhile back, I needed to replace my Adcom five channel amp, and wound up buying and building (eventually), three Class D Audio kits that have done an excellent job for me. Just recently, I had to replace my old Primare preamp-processor, and I bought a nice, used, Arcam AV9 unit for a bit over $700 to replace it.
Back to the amps, for my main speakers, I made one amp using an upgraded power supply, feeding two bridged-to-mono modules, for 5oo Wpc. I am very happy with this arrangement, it sounds excellent, but I have a separate all tube system I switch to when I want to, but for a large portion of my listening, this low-cost solution does a great job.
If you're not too worried about resale, or if you wish to have High End type gear, these amps sound incredible, especially for the price, but may not be for you if you have asperations for uber high-end gear.
Just my two cents. Regards,
Dan