when the price dropped to $400 on a Tascam uh-7000 I took the plunge to upgrade my audio interface.  I have a krk vtx monitoring system (w/krk subwoofer) so I hope that I will be able to hear the difference in the digital conversion and the mic pres. 
 
as has been amply pointed out in my research, the Tascam uh-7000 is not heavy on I/O's.
 
my present (soon to be previous) audio interface is a roland v-studio 100.   at a bare minimum, what functionality do I add to my setup utilizing the digital out of the Tascam to the digital in of the Roland?   does this by pass the da/ad converters and mic pres (in the v-studio)? 
 
I am investigating the possibility of utilizing the roland v-studio as a control surface with the Tascam as an audio interface.   the two avenues i'm venturing down in the pursuit are Mackie protocol (available with the v-studio) and wdm/ks driver to allow utilizing the drivers from both devices. 
 
i'm wondering if connecting the usb's from both devices to a computer and the digital connection via s/pdif between the two would work in theory like connecting the v-studio to an octa-capture? 
 
any other functionality I may be able to gain that my lack of experience is preventing me from seeing?
 
anybody in the same boat?  will be interesting navigating through this upgrade and the one to platinum.
 
thanks in advance for any feedback and/or insight offered.

I have the 7000 and had the Roland in for review.  The Tascam 7000 is a whole step up from the Roland.  It is a half step up from the TC Konnekt unit I also use.  The Tascam is a very high quality unit, both in ADDA and preamps.  The preamps aren't transformer based, so they are very clean, but lots o' gain (a problem w/ most built-in interfaces).  They are simply superb, and I say this as someone who loves transformers. 
 
The only problem w/ the Tascam is a lack of inserts, a rather rudimentary soft mixer and high latency.  And for you, the lack of work clock isn't a problem since the Roland doesn't have one, either.
 
You should be fine running the Tascam out into the Roland.  However,  you won't get the reverse, so your monitoring through the Roland won't reveal the better AD.  But that is the best solution to add more ins and outs in your present system.  Otherwise, I would advise using the Tascam and saving the Roland as a controller.  You should be able to pick the Tascam for audio and the Roland via USB as a control surface.  I forget how it worked, but it did and over USB.  You should be able to use both units at once, but ASIO allows only one hardware driver to work at a time.  And it is a **** to keep switching - since SONAR doesn't always remember which driver I used last (I only use the konnekt if I need more inputs).
 
I strongly recommend the Tascam 7000.  It is the highest quality interface you can get (both conversion and preamps) for the price and that is what really matters.  One can work around the problems, but not pure sound quality.
 
@

I haven't even received the Tascam uh-7000 yet and I've already ordered a tc electronics level pilot.  didn't want to take chances with that volume control situation what it is with the monitors I have. 
half the reason I went with the Tascam was to appreciate my krk monitoring system.  I have the vxt4's and the 10s subwoofer, purchased incrementally so as to afford.  like you, I am interested in sound quality as I want to ultimately record acoustic stringed instruments, classical and arch top guitar to be precise. 
the level pilot is passive and is introduced "after" the signal chain (so to speak) so bit depth rate is maintained in recording/monitoring (at least that's how I understand it).  so I should be able to realize the sound stage those brown burr converters create.   not to mention having separate control over the head phones. 
have had a GAP pre-73 mk2 as an upgrade mic pre over the roland's (vs type) and will keep it for "color" and an active (hi-z) direct in. 
purchased the v-studio 100 because is was so versatile and hope it will continue to be in its new incarnation as a control surface, digital mixer(?), ACT, etc.   with it being Mackie protocol compliant and a driver already recognized in sonar, I understand I can use both drivers (at the same time?) if I use wdm/ks or wasapi vice asio. 
so, what I understand you to be saying is, I can use the Tascam via roland's digital in for it's couple of quality pres but I can't appreciate the ad/da converters? 
would I somehow be able to use v-studio as a mixer to utilize the I/Os  as sends and returns for external effects, the extra inputs, etc.?  am I on the right track here? 
any way I figure I can't go wrong.  the Tascam's are going for $400 now and I was just about ready to spring $300 for a radial tonebone pz pre (which I may still get eventually given my recording interests) and as you so aptly pointed out my sound quality will take a full step up with the introduction of the Tascam uh-7000.
thanks for the feedback.  it is appreciated.  will provide some feedback of my own if and when I get everything hooked up correctly and how it was accomplished. 
 

First, a sound caveat.  The differences in modern converters is small.  It may not jump out at you at first and if you have a lesser monitor system it is even harder to discern.  It is real but small.  The preamps are the same, tho less so.  Until you work with them in different circumstances and drive a better unit hard while hearing a cheaper unit get smaller sounding or break up it is hard to appreciate quality.  The Dallas Sonar group did a preamp shoot-out and when listening to blind files it was difficult to hear any diff, esp. when you were so sure of the difference seeing the test. 
 
But I don't think you will go wrong w/ the Tascam as long as you have the money.  If it was just converters, that is a lot of money.  The preamps should be a step up from the GAP, which are more of a one trick pony, but it is nice to have the transformer sound available.
 
You should be able to run the VS-100 as a controller, I think.  Like I said it was many moons ago when I had it here.  The moving fader is brilliant, and smoother than the one on the 700.  And I almost wish I had kept it since I do some remote recording these days and it is a good unit for that.  I just find that unless I need more than 2 inputs here at home it is easier to just work w/ the TASCAM even with the latency.  The couple of times I've used it and the TC unit at the same time the two units don't sync well.  The TASCAM stuff was fine but the TC had clicks etc., which was fine since it was a scratch vocal.  the Tascam was set to automatic and the TC was master so I need to figure that out - I do have a drummer coming over soon.  So I don't know how it will sync up audio wise w/ the Roland.  The cake is like the future, as Boorman's Merlin says in Excalibur, you don't know what it taste like until you take a bite.  And then it is too late.  It should work, I just ain't eaten enough to be sure.
 
I've always found ASIO to work best, so I don't know about waspi and WDM etc.
 
Good luck.
 
@

From the spec sheet:
 
The link line function allows the line output volume to be adjusted using the headphones volume knob. This allows users to connect the unit directly to powered speakers and adjust the monitoring volume without need for a mixer or other equipment. 

Yea, sorry, didn't get that.  Yea, you don't need the pilot - one (small) knob can control both vol levels, although mistakes can be made.  There is a small light that shows the status of the vol knob, but it is simple to overlook. The TC unit is very good - a friend in a major studio here used one in his B studio when his A studio SSL was out of commission.  He really liked it.