Upgrade PWD MKI to MKII worth the investment?

Yes, it is worth the investment. Bass and dynamics are much improved. Use firmware version 2.0.2, as the latest firmware sounds fatiguing to me.

I thought PS Audio had stopped selling the MK2 upgrade, or only had a few kits left.

I will answer your question with some dialog from the classic scene in Katz's deli from When Harry Met Sally. "Yes, Yes, Yes!!!"

Just the Native X feature alone is worth the upgrade. Enabling NativeX (from Native, which is the best mode on the MK1, takes a digital signal which is a bit congealed and opens it up to allow each instrument to exist in it's own acoustic space. It may be considered on the subtle side at first, but as your ears become educated to how digital sounds with such low jitter, (under 1 picosend I believe) the effects is not subtle. Even standard redbook audio takes on the quality of hi res material. It's pretty amazing. As HIfiAl states the benefit may depend on your system. My monitors may have a "tad" more resolution than yours, so who knows.

I am using it with the bridge, not the other inputs. I can't imagine how the MKIII could be improved other than support for DSD.

Well, I will give it a go.

First you must use the Native X setting to get the full potential out of the upgrade.

If you have a PW Transport and use the I2S output to the PW DAC you will get a CD player that will beat all but the best and still rival them.

The fact that all inputs have the Lens Tech makes this a worthwhile investment IMHO. It improves the sound for all inputs.

You will hear a more refined sound. Better dynamics, sound stage, more transparent, less digital and I think more musical.

Will it be night and day? I guess it depends on your system.
I felt it was worth the upgrade. Keep in mind it will need to be burned in again as you have a new board.

But there are other things to consider.

PS Audio is working on the next upgrade. When? Anybodies guess. I would say no earlier then end of this year. No later then end of summer of 2014.

But when that happens you might pay more to upgrade on a MKI vs a MKII I would expect.

Then there is all the other DACs that have and will be coming out in the next few months in the $4-5,000 price range.

If it cost you to upgrade now about $8-1,000 and then to the MKIII another of the same you would be around $1,600 to $2,000. A lot less then what you would have to spend for a new DAC that most do not offer a hardware upgrade path.

I would expect the same worthwhile upgrade in sound from the PS Audio MKIII when it come out.

What ever you decide good luck.

I did but I did not get much response either and some were ambiguous,
I like what I hear with the mkI, but I was expecting description of sound difference.
Thank you very much.

OK, I found that recent thread:
PS audio PWD MK2 a real upgrade from MKI?

and it was started by you. That's probably why this one didn't get much response.

There was a thread about this recently but I can't find it for some reason. In that thread I said I thought the Mk II was a definite upgrade but not a night and day difference.

A few people thought I was deaf or crazy, and I admit to being a little of both. They thought the Mk II was definitely a night and day upgrade.

You can find this discussed in great detail in the discussion forums on the PS Audio website.