Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems HD621 Does it support 4K?

Yes I have tried this for listening to 2 channel music. It sounds the same as routing via the HD621 which does the Apodising and FIFO buffering, instead of the 861 doing the apodising directly. The shorter path, lower jitter and ground isolation of direct optical connection to 861, instead of HDMI via HD621 to 861, did not make a difference to my ears.

The DAC and output stage in the analogue XLR output card of the 861v4 are beaten by the upgraded Oppo. It may be the other way round with a newer 861v6 or 8 analogue XLR output card?
But with the ultra low jitter and noise, in the Audiocom Oppo and all the other improvements, plus a better DAC chip, including separate PSU; it is probably unfair competition for the old v4 XLR analogue card.

However i may be upgrading to an even more superior external DAC to feed my Stax head amp, and Earspeakers. So this will also beat the DAC/analogue output stage built in the upgraded Oppo. Will be either an MSB or a lampizator external DAC.
Both these use discrete low noise super accurate ladder resistors to do the PCM D/A conversion, and do not use a DAC chip or op amps. It is all discrete components. Same ones as used in satellites, instrumentation, and military systems where accuracy is essential.

The reality is most DAC's are not ultra accurate. Modern Sigma Delta DACs use high speed mathematical guesswork, and need an accurate clock to keep jitter low.
Older more expensive to manufacture DAC chips from the 1980's/early 90's based on a Ladder resistor network were also not highly accurate, though they were very fast as no processing was involved, and they were not so dependent on clock accuracy (low jitter) to get a good sound.

What will be interesting is taking the apodised/FIFO buffered digital coax output from the tape/bypass out of the 861 and into the external DAC.