FWIW a CTH 8550 just came up for sale on usaudiomart. it won’t last long. One thing to note is that it’s really designed to be used single ended for best results.
DartZeel CTH-8550 vs PS Audio BHK 300 Mononlocks
I know this is a crazy comparison but I am currently trying to decide between the Dart 8550 Integrated (used) or a new set of BHK 300 Amos with the BHK Pre (new). I am currently upgrading from a Yamaha A-S3000 and like convenience of the integrated but feel like the BHK monos might be a bigger upgrade. They will be fed by a VPI HW-40 turntable and a PS Audio DirectStream and will be running a pair of Joseph Audio Perspectives.