Both these products start with TASCAM hardware but I wonder about any differences between the two internal DACs.
Now that my PrimaLuna amp has sold I'm looking at using the funds to upgrade my Emotiva DAC.

Both are using Burr Brown DACs, however the ZDSD is dual mono.  The most noticeable difference is an increase in density.

I feed the digital output of the ZCD240 into the ZDSD and use the ZDSD as a DAC. This makes it easy to run RCA cables from each unit and do direct A/B comparisons. The variable output on the ZCD240 is an advantage, the dual mono on the ZDSD is an advantage, each worth close to the same amount of points, so in the end the two rank very similar.  

The combo is of course the best and can be created with a stock CD240 and a ZDSD. I particularly enjoy the high-res streams from the ZCD240 from either unit,  But the added density of the ZDSD as well as the record button is damn handy to record whatever you're hearing. You can fit around 15 hours of 24/96 stream onto a single 32G SD card.

I'm going to order one!
http://www.bhphotovideo.com/c/product/1079892-REG/tascam_cd_240_cd_and_network.h...

Jitter reduction + streaming. I will be using the Coax digital out (Illuminati D-60) to my stellar Decware ZDSD and my AURALiC Vega coming! My Vega might want a better lock on the Digital Coax output to input anyway.

I can tell you though, I don't use the Sony I'm running cause' it sucks. IT bested: Marantz, CEC & a couple others too. Thus, why I use the inexpensive little bugger. But, the little SONY that has beat others,  should be bested by the 240 a little in the jitter department and obviously I'm getting it for the other capabilities (in which I will get around too~Winter is long and very cold here in the great North Woods)!

Whatever you decide Core, between Steve's 240 or 3000....I am very pleased with the price of admission for the ZDSD (read: Steve's Output Tranny's = musical thru the Wazooo).

I love the sound of the ZDSD, but the CD player just can do more, and costs less.

Keep in mind, neither unit is a regular consumer product with intuitive menus. If the CD player had a full blown web interface that allowed you to connect it to my NAS and a simply playback/settings, I'd be ordering one right now! They are professional gear, and I find them a little clunky - but they both sound way, way better than their price points.

The CD player does have a very basic interface that allows you to input internet radio stations - which I like a lot, but I don't think you can do Tidal on it.

If you can see if Tidal has a streaming URL I can try and plug it into Steve's CD-240 that I'm testing and playing around with this week.

I'm assuming that you haven't forgotten about the free app for your smartphone to control the ZCD240!  It's pretty nice to see album art and meta data as you listen not to mention have complete control over the player.

Do any of you users of the ZDSD know if you can record one digital input track while playing a track to the RCA outputs?
Not simply monitor the recorded input but play a different track?

Core32...I use TIDAL as well.  I think it sounds great and I am still trying to figure out the best way to pipe it in to my main system.  I was leaning toward an Auralic Aries.  I also recently read that Audirvana is working on TIDAL integration.  

Streaming is the wave of the future, so I suspect there will be a bunch of options in the not too distant future.  It might be best to sit back and see how things shake out.

Dang! I just realized I called Dave, Mark....senior moment. Sorry about that.

For a few days I've had the chance to play with a TASCAM DA-3000 and I will have access to it for a few more days.
This is the model Steve modifies into the ZDSD.
Even without the Zen mods the DAC in this unit easily bests my Emotiva DAC in sound quality.
The improvement in channel separation and stage depth is immediately noticeable along with the increase in bottom end definition.
On true DSD playback I've had to back down my sub amplification by 2 to 3 dB.
The Emotiva controls are much easier to navigate, but it is only a DAC and designed for home use so should be simpler.
A few interesting items I have observed (and believe to be true) about the TASCAM are:
1.) The standard digital inputs cannot be directly up-sampled to DSD, only the analog inputs or SDIF-3 inputs. The menu will not let you choose otherwise.
2.) The standard digital inputs are limited to pure PCM data only. I could not get DoP to work. This could just be my unfamiliarity with the unit.
3.) DSD data cannot be input to the DAC except via the SDIF-3 input. This is not a major issue because DSD is playable from SD, CF or USB stick. It would be interesting to find some SDIF-3 (or DSD-Raw) compatible source but they appear to be vaporware in my Google searches.
4.) The unit does not appear to automatically switch between PCM formats, though I did have confusing results with this. It may have done the switch but indicated an error with the color-changing INFO button. I tried too many options in this area and it may just have been another case of not knowing what I was doing...  

None of these are deal breakers for me, just observations of things I did not expect.
If anyone is aware of HW I could use to test the SDIF-3 BNC inputs with DSD that would be great.
Otherwise you just copy the DSD music to FLASH media and play from there.