Proceed AMP5 upgrade?

I have had an AMP5 for about 5 years now, bought it used. Its performed wonderfully for home theater and not bad at all for 2 channel. I have recently started moving down (up) the vinyl rabbit hole, and use a tube based preamp from Response Audio NY (custom). I then upgraded my Dual CS-5000 to a Micro Seiki RX-1500, Zyx UNIverse cartridge (love), DP-8 tonearm (love) and most recently took delivery of a pair of Wilson Sophia v.1 speakers.

I can't help but think my amp is now the weak link in the system.

What should I replace it with? I have space for one room with both audio and video needs.