I've been looking at this unit. They make a big deal about the audio quality of this interface in the adverts. Special components and extreme build quality. At just under $600 in Canada it's pretty expensive for a 2 channel interface and there's no mention of latency specs. I'm thinking of getting one just for vocals and don't have a pre-amp so it could be cost effective.

Great conversion and even better preamps.  No, they aren't transformer-based but still a head above any other built-in pre I've used.  Plenty of gain.
 
I bought a second one for @$350 US from GC w/ a 15% rebate last year. I don't know what the exchange rate w/ CA$ is, but they are pretty cheap for what you get.
 
The downers - latency is pretty high @ 11 ms or so.  It is still usable, and you can digitally wire it into a faster interface w/ either AES or Spdif.  Also, you can't use two units together as a single unit, connecting them digitally, since the 2nd choice of "automatic" to sync them kills the digital input (one unit can use 4 tracks from your computer). I've managed to get 4 out and 2 in, which is mainly what I wanted for buss/outboard duties.
 
Another point is the other TASCAM line - the US, is just about as clean and good for conversion and pres.  Close enough for government work and you get 20x20 for the same $400 US (on down).
 
If your main concern is sound quality, it is the best unit around for the price (note: I've never used the crimson etc. units, which are supposed to be of similar quality).
 
Read more at Tape Op if you want my unit review, but the above are the high points.
 
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Thanks for the response. I was a bit concerned about that latency. My Steinberg/Yamaha is 9.5 ms, so pretty close.

You should also look at the Audent iD14, which has gotten rave reviews for its sonic fidelity -- and it costs less than the Tascam unit.
 
http://www.sweetwater.com/store/detail/iD14

I had one for a while and agree that sonically, that unit is outstanding for the price. As a headphone amp alone, it's the best I've heard. However, with a streamlined studio I eventually opted for a RME for shorter latency since I use outboard preamps for the most part.

What specific reason has you looking at the UH-7000?  I see you currently have a Steinberg UR44, which is a solid unit all round.  Pretty much anything under $1000 is going to be a lateral move.

JonD
What specific reason has you looking at the UH-7000?  I see you currently have a Steinberg UR44, which is a solid unit all round.  Pretty much anything under $1000 is going to be a lateral move.

THey claim that it has sonic superiority and special DAC's. I have no issues with the UR44, it's mostly curiosity.

Again, the 7000 is a better unit than garden variety converters.  How much is an individual thing - without good monitoring it is hard to hear any difference.  And when you get right down to it, there isn't that much difference between low-cost units and the 7000 and a Burl etc.  None of those units will ruin a take or mangle a mix, so it is a matter between good and gooder. 
 
But 2 years ago there was nothing on the market as good for the price and if you want to squeeze the last little bit of sound today without spending thousands of dollars, it is still a great way to go.  You will be able to hear a little clearer and deeper into the mix, and the pres let you back off the mic and use more positions to record (when the room becomes important - it is all linked together).  Whether you want to spend $400 on a stereo unit or an 8-banger is an individual choice, as is getting simply sticking with a cheaper stereo unit.  I'm more of an engineer than musician, so that was an easy choice for me.  If I played guitar I might get more "bang for buck" saving for a new guitar.