I got my USB to serial adapter with FTDI chipset from here

It works perfectly with my 568.2mm and my DSP5Ks. But they only deliver to Europe.

Frank

Main system:G65, 218, HD621 2 x DSP5200SE, 1 x DSP5200HCSE, 2 x DSP5200SL, Power Sound Audio S1512, DSP Anti-Mode 2.0 Dual core, NuPrime H16AES, 518, Dune HD Homatics Box R 4K Plus running CoreElec 21.3, Oppo 103D and SqueezeTouch. Atmos, MQA and Trifield! smile