If the DMP is connected to DSD with an HDMI cable, I recommend connecting the masses of both devices with a short cable, preferably pin-1 XLR Digital Output - pin-1 XLR Digital Input. If this has been discussed, I am sorry to discover America for the second time.
Why is this ?
Maybe for a cleaner grounding scheme to reduce rfi?
I think Ted has mentioned to disconnect all connections from transport to dac…when using hdmi …for better sound.
There was a significant improvement in sound quality, the bass gained a lot of precision. DMP with DSD can be connected with an XLR-XLR cable, but only the pin 1 (GND) of both connectors is relevant. I checked the connection with the Coax cable, but it’s not as good as the connection between the XLR connectors.
I have a HDMI WW Platinum Platinum Starlight 7 cable.
Interesting. Thanks for the explanation.
It seems to me that this was a recommendation and until now I only had an HDMI cable connected. I accidentally found that combining the masses of both devices significantly improves SQ. I hosted the Polish PS Audio salesman and he was very impressed.
My system:
P5, DMP and DSD (Windom) with SR Blue fuses. At home I have a special power line for Audio equipment. All power cables are Verastarr Grand Illusion Signature. Active 3-way loudspeakers assembled by me (enclosed enclosure, weight approx. 55 kg, Scan-Speak speakers: beryllium tweeter D2908 / 714000, midrange 18M / 8631T00, woofer 28W / 8878T010), IsoAcoustics Gaia II. Loudspeakers connected with Van den Hul Platinum Hybrid balanced cables. Before the cables at the DSD output I have symmetrical buffers that I have assembled on OPA1632 amplifiers. They have low output impedance, excellent parameters and significantly improve the sound in a system without a preamplifier, even with the best cables .
Sorry for my English. I hope you understood me.
Very nice setup:)
As a Do it yourself fan I’d like to see circuit diagram for the buffers, and wondered what volume (litres) the loudspeakers are?
Sounds like a good system anyways 
…and no problem if you want to keep the details to yourself 
Still not sure I uderstand. Do you mezzanine you connect 1 single pin xlr cable between dac and transport, and if so did you make the cable yourself ?
Only pin 1 of both XLR connectors should be connected. Preferably a short cable of almost any thickness. I am an electronics engineer, but any soldering iron owner can make such a cable.
I attach photos of my system. On the back of the loudspeaker I have a module with an analog 3-way crossover (24 dB / oct, 180 Hz, 2700 Hz), 3 Hypex NC 500 amplifiers, Hypex SMPS 1200 +/- 85 V power supply. The housing has 45 mm thick walls. The woofer works in a volume of 45 liters. At 40 Hz I had a decrease of 3 dB, but I installed a filter amplifying the lowest frequencies and currently from 25 Hz to 180 Hz the efficiency is in the range of +/- 2 dB.
Much respect - that looks like an excellent job
I looked at some analogue crossover modules but ended up going with a dcx, for now at least, using regular hifi amps (90s amps are cheap on eBay!) But have been looking at some class D modules to replace them
So just 1 cable ? From xlr digital to digital ?
Has anyone else tried this and confirmed the OP’s findings?
Try this solution. You can connect any cable with XLR connectors. Write how this affected your system’s sound.
@wiesiek - I had some time over the Christmas break so I thought I would try this extra ground between the DMP & DSD. In addition I wrapped the 14ga wire with 0.5in braid to make sure I covered HF GND. I listened for a day back and forth and found zero benefit. I took pics to show the approach.
Furutech XLR connectors w/ braid & 14ga wire.
Very short cable from DMP to DSD.
This had zero affect. However, thanks for the idea, I left it in since this took me a few hours and $75 to implement. More love from the desert!
Thank you for the report. I expected this result, but it was worth trying - here, elegantly.
@Elk - yeah - thought so myself and had a few calories to expend. All systems are different. Grounding schemes are different and component set up is different. It adds an extra GND so it does not hurt. I thought I would provide feedback to the collective so others think twice. In the end, adding a second GND is not detrimental… hope you are having a great holiday?
I also expected no downside and, as you note, grounds vary so it was wroth a try.
I do particularly enjoy how pretty you made the setup.