@jamesh - there’s been some ongoing discussion of physical shorting of unused inputs on the DS1 and now 2 - having positive sonic effects. Ted mentioned that turning off unused inputs may be implementable in the UI SW, if I read his post correctly. So if that were possible, and it had a similar sonic effect to physical shorting, seems like it would be worth doing, from our POV.
Of course for those of us using most of the inputs, it may be a matter of indifference.
I’m still kind of semi-patiently awaiting the next software update for my MK II… PSA Engineering thinks that the muting in my unit is software related, and so far they’re not asking me to send it back to them.
Prior to yesterday, I hadn’t installed the software update that Aaron emailed out on the 2nd, because it wasn’t intended to fix muting issues. Yesterday, just because I couldn’t do anything else with my Mk II, I decided to install the software updates.
Since installing the updates, I’ve yet to be able to get any audio output. I’ve tried both USB & coax inputs, and neither works. My source is an Aurender N100C, and I’ve tried all different sample rates & file types that I have available. I tried again this morning, after the Mk II was powered down all night, and still nothing. The display shows the correct bit depth & sample rates, but no audio.
I have yet to try using the I2S inputs, as I’ve got my DMP boxed up to ship to PSA (I traded it in against a pair of FR-30’s, which I LOVE…). If anyone thinks that the I2S inputs might behave differently than USB or Coax, I’d be willing to give it a try today. The box isn’t sealed yet, so not a huge deal.
In total, I’ve probably gotten to listen to the Mk II for ~3 hours, intermittently between muting, then having to power it down for hours at a time before it would work again. I’m more than just a little envious of the beta testers who haven’t had issues with muting, and have been able to enjoy their music. I’m trying not to get frustrated…but it’s a challenge…
You need to send your unit back to PS Audio. @aaronm can set you up.
Referring to the MK2. Well this is design dependent, might be a resistor versus a shorting plug. @tedsmith would know if these unused inputs were shorted what it would do to the circuit. From what I hear these inputs are IC switched. I’m sure that Ted is following the manufacturer’s recommendations for proper termination when switched. Excuse me if I missed the point being made. 
Bummer. Well, at least you tried.
@badbeef’s response nailed it. Ted believes it’s technically possible to turn off unused inputs but it requires a UI update to implement. IMHO there can’t be that many users who are going to use all the inputs. For instance, when the dust settles and we are in General Availability (GA) I will most likely only use one input. It’s a stretch for me to seeing a majority of users using two 12S, and USB. Sure there are some, but a majority?
It seems to me that it’s in PSA’s best interest to make the MKII as quiet as possible.
[Edit - I type slower than vkennedy61]
The hardware supports powering off the unused inputs (and for that matter powering off the ethernet stuff as well.) We just need to expose that in the UI.
With that software change the Mk II won’t need input shorting plugs, but they are safe and effective now before the software is out. The Mk II has more hysteresis than the DS so shorting plugs (as opposed to ones with resistors) for inputs are the best thing. The details are on the DS Mods thread and jkrichards has a thread for people that might not want to build them themselves.
FWIW the RCA and XLR digital inputs are transformer isolated and a shorted input will cause the least possible chatter in the comparator. The I2S inputs use a LVDS receiver that has an explicit feature to not chatter with open circuit non-driven inputs, shorted inputs, or terminated inputs. But I know from experience that open inputs sometimes look like they have real data if the interference is too structured.
I have used Cardis caps on XLR and RCA inputs on my previous equipment. When I got BHK pre and DS I kept them on too. They would lower the background noise to make the sound cleaner.
However, when I removed them, the dynamic and soundstage made a noticeable SQ jump! The music is more vivid without losing any clarity. Now I could not put any of them back. The USB shorting plug (HDMI I have not used) is different. It improves the sound without any limitation on dynamic. So, USB (maybe HDMI) is the only one I will use.
The fuse spec is stamped on the back of the DAC. for 120 volt it is 1 amp type H slo blo.
Ted,
Since you’re way ahead of the beta group, has (all else being equal) your development and testing of the MK II lead to a SQ preference for one set of inputs over the others?
These days I have a > 70dB hearing loss from 3k up in both ears. I work based on math and double check with my wife and daughter. Also I need long flexible interconnects from my work bench to my system, I use the ICONOCLAST related BAV for that, but they aren’t the most transparent. I like to make differences bigger than the difference between inputs with each software release and I need to use all inputs for testing, so I don’t care which input I’m using.
Yeah but . …
I’ve heard stories about symphony conductors with profound hearing loss from decades of standing in front of full orchestras that can still pick out a third violin in the back row with an out-of-tune instrument.
I still feal some jitter differences, if that counts. 
Yeah, that puppy will definitely need to come in. The repair team has been putting these at the top of the queue so they haven’t needed to be here long at all.
I cannot compare SQ between USB and I2S anymore. It turns out the FOUR USB ports on my Euphony Summus 2 are all inputs! Who would have thought all four are inputs? Okay, I did not read the menu.
I just received the beautiful Silnote Epirus Elite Master Reference USB cable, and it is useless. I will keep it in case I want a streamer with USB output in future.
@dchang05: I am unable to even take in the potential effects of this post on everything you have posted with regard to the DS2 prior to this point.
A great feature and I hope it is, indeed, implemented.
Keep up the good work, Ted!
Haha, my journey is near the end. I’m ready to jump into the tweak thread of MK2 soon!
Ha! LOL.
Just sent an email to all beta testers with this! Our final software is ready for you guys!
Hello all!
We are very excited to announce the full production release of the DSD MK2 firmware! I have included those files here on this email.
A few things to note about this final software:
With this firmware release we will conclude beta testing on the DSD MK2 in the next few weeks.
Thank you all again for being a part of this! We are very excited for the future of PS Audio and the DirectStream DAC MK2!