Melco Audiophile NAS

[DavidHB]

(10-01-2015 18:57)beckphotonik Wrote:  I suspect it is more than just electrical isolation. My guess, and it is a guess, that the Melco does some form of IP filtering too so the streamer gets only the audio and control packets it needs and nothing else. How and why that should make a difference I don't know but from what Simon has reported, something interesting is definitely going on.

My guess - again no more than a guess - is somewhat different.

It's (relatively) easy to verify that the data which is arriving at the player is bit perfect. What is harder to verify is that it is arriving at the DAC at a time when the player's timing controller can actually ensure it is decoded at exactly the right instant. We know that caching is supposed to take care of timing differences, and does so, at the gross level where the player would otherwise be waiting for data. What we don't know is whether there are other timing issues (jitter) that caching cannot handle completely. Melco are claiming reductions in jitter.

The published data suggests that what is different about the Melco port is that it incorporates an opto-isolator. This, presumably, filters out electrical noise and so 'cleans' the data stream reaching the player. If the combination of Ethernet port, timing controller and DAC in the player can handle this cleaner signal more accurately (that is with less jitter), there could be sonic benefits.

My understanding of RTP (the network protocol used for media streaming) is that packet filtering would only prevent packets being sent to the player which its network controller would not accept in any case. I can't really see how that would affect sound quality, or indeed how it could explain the change that Simon noticed when he used the Melco cable. So my guess, as it was at the top of this thread, is that whatever is going on relates to electrical noise/signal quality/timing/jitter. But, although it is consistent with what Melco say about their product, it's still pure speculation.

On a quite separate point, it has occurred to me that the Melco architecture does have one potentially serious limitation. That is, with only one port to serve a single player, the NAS can only provide its particular benefits to one room in a multi-room system. So, if Simon's preliminary findings are correct, what we actually need is not so much an audiophile NAS, but audiophile switches at every node to which a player is connected. Or maybe the LAN isolators mentioned by best - a snip at $464 each, if I understand the pricing correctly. That's still a fair bit cheaper than a £6,200 NAS, however.

David