Denon and Marantz to ship out free 'adapter' to fix AV receiver HDMI 2.1 bug

Good news for owners of 8K-capable Denon and Marantz AV receivers who have been frustrated by an HDMI 'bug' affecting 4K/120 playback from their Xbox Series X/S console – the AVR makers have confirmed a free fix, in the shape of an external HDMI adapter.

Dubbed the SPK618, this adapter will sit between the gaming console source and the receiver, and deliver 'corrected HDMI data to the AVR, thus remedying the error and allowing a 4K/120Hz or 8K signal to pass.'

The SPK618, which requires mains power, will offer a single HDMI 2.1 input and HDMI 2.1 output, and will ship with an HDMI cable. The box is described as 'low-profile' – but is still another box to find space for.

Denon and Marantz parent company Sound United says the SPK618 adapter will fix the issue that's affected the following receivers and processors:

  • Denon AVC-A110
  • Denon AVC-X6700H
  • Denon AVC-X4700H
  • Denon AVC-X3700H
  • Denon AVR-X2700H
  • Denon AVR-X2700HDAB
  • Denon AVR-S960H
  • Marantz AV7706
  • Marantz SR8015
  • Marantz SR7015
  • Marantz SR6015
  • Marantz SR5015
  • Marantz SR5015DAB
  • Marantz NR1711

Says Sound United: 'Customers who have an affected receiver will not need to ship anything or retrofit their products at home.'

Anyone who wants to receive one should head to or for more info.