For your balanced cables, are you using stereo 1/4" cables or xlr?

xlr cable with an adapter for 1/4 (trs) to XLR at the Steinberg side.
I was having very bad interference, which I'm guessing was the video, flourescent lighting I had on.  Went completely away when I swapped cables.  StudioCat suggested better USB cables if having problems as well.

btw, I just used some mic cables, which are probably way to light a gauge wire, but seemed to be OK.
 

I received a replacement unit from Sweetwater (those guys have been excellent at service and support and I highly recommend them.  Their prices are great and they have a 2 year warranty).  
All mic pres are good.  I am getting a pop sound when turning the unit on and off.  Steinberg says that is normal and that is why they recommend turning speakers on last when turning the UR44 on and then turn the speakers off first when turning the UR44 off.  Makes sense.  
 
The unit is performing great with Sonar X3, Studio One 2.6, Cubase AI 7, Cubasis 1.7, and Auria.  
I can highly recommend this unit.
 
Rimshot
 
 

Mine sounds OK, but I'm finding the mic pres don't really have enough clean gain.  I'm trying to use a lower output RE-20 dynamic, and I have to crank the pre just about all the way up. I've experimented trying to "make up" with their little built in channel strip, but it just adds noise really instead of clean gain.  Wonder if a Cloudlifter CL-1 would help.... at half the price of the UR-44!
 
I know there wouldn't be enough for a SM7 or a low output ribbon too.  Took me awhile to find the "loopback" so my screen capture could record system audio..  but works good.  Only nit is I'm guessing it only has about 45-50dB of clean gain.

I have read that using an SM7 generally takes alot of mic pre gain to get it going.  I use a B1, SM57, SM58, and Rhodes M5 mics without any gain problem at all.  The Yamaha mic pres are super clean.

I've tried a 57 and a 58 and had to crank them up almost all the way too...just for narration and being about 6 inches from the mic.  No way I can get the peak lights to light up, with just a voice, unless I'm screaming loud.  Otherwise, I'm just starting to get a waveform in Sonar...A good 30dB down I would guess.  I'm going to experiment more with other pres going into the UR44 line ins.

In our broadcast studio I have to run our RE27 through a DBX channel strip with 50 dB of gain before it goes into the UR-44 I just got for it.  The D-pre's sound great but they are of little use above 50 dB.  The same could be said of most interface pres.  The DBX was much quieter at the higher gain settings, so the staging was much quieter with the channel strip carrying all the load.  

Yeah...I plugged a RE-20 into another pre...actually a cheapie Yamaha mixer...and barely turned it up to keep the inherent noise down on that pre.  Then the UR-44 only had to be turned half way up and the levels were great.  I ran ALL balanced lines, and that helped keep things quiet.  I do quite a bit of narration, so I think I'll be experimenting more with a gate or expander as well with this newer setup.
Yes...I agree...I got what I guessed to be about 45-50dB of gain...then the "ocean" became quite apparent....plus I ran out of rotation on my gain knob ;-D

BTW...I've had a pile of old Echo products.  Their pres were nice....my latest being a 3G... but no gain.  Ribbons could definitely NOT be used.
 So I agree that probably many lower priced pres on audio interfaces won't cut it.