Help me pair the KEF R11 Metas...?

I’ll start by admitting that I am a fan of @therecoveringaudiophile aka. Andrew Robinson.

Some may consider him a pseudo-audiophile. While that may be true on an absolute technical side, his eloquent delivery, production quality and rapport with his producer-wife Kristi, make him my favorite source of audiophile information.

In any case, he knows more than me, so I trusted his review of the "TOP 5" floor-standing KEF R11 Meta speakers.

I picked them up NEW at 45% OFF from an audio dealer in Miami I did a favor for. Stealing them for $3,800 a pair...in white.

The plan was to connect them to my existing Cambridge Audio Azur 840a Class XD, 4ohm, 200wpc integrated I’ve had and loved for over 10 years connected to a pair of Definitive Technology Mythos STS towers. This specific combination sounded amazing using Bluetooth or vinyl.

I assumed the KEFs would be a major upgrade.

The KEF R11 Metas and the CA Azur 840a simply did not pair well, for reasons I still cannot explain. The sound was flat and low and I would have to push the amp to 90% volume to get the KEFs to sing, but then the amp would either short out or show a clipping error.

I checked all the connections, settings, and even reached out to KEF for help, which they gladly offered, but nothing seemed to help or explain any of this.

Out of frustration, I pulled a Technics SU-G91 Class A, 8ohm, 125wpc integrated from 1992 out of my closet, just to try something different.

I replaced the cables as well, switching from custom audiophile speaker cables, to simple OF bare copper. I then connected a new Cambridge Audio MXN10 DAC/Streamer as a Tidal source, instead of using Bluetooth, and let it rip...

OMG....night and day better.

Finally the KEFs seemed to be living up to their reputation. Brilliant sound, clean, smooth, a real pleasure to listen to...at normal volumes.

But...that left me with a question.

As an amateur "audiophile", I’m struggling with all the endless reviews online vs what I’m hearing at home with this setup.

With a desire to maximize the $6,000 KEFs potential, should I be looking to replace the $300 "vintage" Technics SU-G91 Class A integrated amplifier with something else?

Can this strange pairing between the new KEFs and the old Technics really be this good?