Soliciting Opinions - Scarlett 18i20 vs Behringer UMC 1820

more expensive,
but a step up,
would be a RME UFX
 
 
OTHERS:
tascam celesonic
motu 8pre
steinberg  ur824

This may not be much help as I've never used either of those specific models...
I've owned both Behringer and Focusrite products before, and the Behringers have always felt cheaply-made and have worn out/ broken fairly early.  My Focusrite interface is sturdy and reliable.
Perhaps Behringer build quality has improved in the last couple of years, but I'm very wary of them.

The issues the person was having with the Tascam ( I was part of that thread) were seemingly more a system issue than a Tascam driver issue. Not everyone has problems with that interface, but still I don't blame you from shying away. Behringer, even though I know they may have improved, is the only equipment I ever bought that totally failed on me before I got my money's worth, so sorry, not going to ever trust them again. 
 
I've narrowed my search down to a Motu Ultralite Mk4    http://motu.com/products/proaudio/ultralite-mk4  
It's a price jump but I think it's time I got out of using less than perfect equipment. 
 
RME is another company I would go with. 
My Focusrite 6i6 is a great interface but does not have enough inputs for recording drums or a band. I still use my old Tascam us1641 for this without issue. Both suffer so, so pre amps and not great RTL performance. 
I'd like to take the next step and do it right, so Motu and RME is where I need to go. The Motu unit would also serve double duty as a live mixer with remote control capabilities.
 
If all you want is more XLR inputs for recording drums you cannot beat the price of the Tascam's. 
 
 

I used to dislike Behringer quality but my X-Touch is very well built.
 
I have several Focusrite Scarlett interfaces including the 18i20 1st gen. and all work great.  Support is excellent.  Be sure to get 2nd generation models.
 

Well, I didn't plan this to happen.  Dropped into the local Guitar Center today, and somehow ended up walking out the door with the brand new Focusrite Scarlett 18i20 2nd Gen for $360 out the door.  Was $450 at SweetWater, so I feel like I got a pretty good deal.
 
Got it hooked up tonight, and most things are working, except playing back audio tracks.  The Focusrite is set correctly in the preferences, but still no joy.  I'm sure I have something set wrong, I'll go through the manual tomorrow AM.  I'm just new to all of this.  This is clearly an upgrade from my Tascam.
 
I see folks report their latency - can someone explain to me how to do this?  Is it done within Sonar?

Got it all working now.  Thank you.  One follow up question....
 
And I know this is probably an impossible question to answer, but what is a good "starting point" for Sample Rate and buffers?
 
I do mostly audio out of my FA08 and Moog, as well as some VSTis.
 
At 44.1 and 128 buffers, I get around 13.1 ms round trip. 
At 96 KhZ and 512 buffers, I get 50.7 ms round trip.
 
I don't have much experience, but are these in line with what I should expect?

Thought I would chime in here. I have used both the UMC 1820 and the Scarlett 18i20. You can achieve better round trip latency with the Scarlett depending on your system. On my desktop I use a pci express card for USB audio devices, all the USB processing is handled on the card and there's no sharing of bandwith with other usb devices. This will go a long way in helping to get low buffer settings to work smoothly and dropout free.  With the Scarlett I was able to get the buffer to 32 and it was stable for me (but see below). The lowest the UMC 1820 will go is 64 but I really couldn't hear much of a difference when monitoring between the 2 at those settings. Both units sounded very similar, the Scarlett pres are a tad bit warmer to my ears, but I use several external preamps so that's a not an issue. The Scarlett is bigger and built like a tank, but the Behringer is not a cheap build at all the only real drawback being wall wart power supply. Both units handle ADAT without any issues. One thing the Behringer has that I like is each of the 8 channels have line/inst switches as well as pad switches. The Scarlett only has those options on the first 2 channels. The Behringer also has a knob to adjust between the direct signal and the input monitor signal from SONAR whereas the Scarlett only allows control of that in their software. Not a big deal either way, but the software with the Scarlett let's you set up a lot of nice mixing options for monitoring. The Behringer doesn't come close on that.
 
Unfortunately both me and one the other producer where I work had to return the Scarlett units. We both had issues with the devices losing connectivity in our DAWS and both of us had issues with odd noises coming from the unit when engaging the transport from time to time. He was using his on a MAC with Pro Tools, I was using it with SONAR on a PC. Not sure if these were just bad units or there were driver issues. So, while I still think the Scarlett is the better unit, the Behringers have performed better for us and the cost saved us some $$. Your results may (and probably will) vary.
 
 
 

I do own a Behringer UMC404 which is a smaller version of the 1820. It works well with Sonar, the preamps are quiet and sound as good as you'd expect from Midas. 

Don't let bad impressions of 1st gen Behringer crap fool you, since they acquired Klark Teknik and Midas, their know how has grown considerably.  They still have some weak products but this sound card isn't one of them.