Hi Beepster, just thought I'd update you on my progress...   
 
I've had the 18i6 running since Wednesday evening, and except for a glitch in the first hour of setup it's been running well.   Here's what happened - After getting the drivers and MixControl installed and updated, SONAR recognized everything just fine.  I then tried the Hi-Z input with bass and guitar to see how that faired... about 10 minutes in I suddenly lost the connection to the 18i6, both in SONAR and MixControl.   I tried unplugging and replugging the USB cable, rebooting a few times, etc, but none of that worked.  The only thing that did work was cycling the power to the unit.   But I've now had the 18i6 running constantly since them without any further hiccups.  Whew.
 
I did notice a bit of noise when turning the Input gain and/or Headphone volume way up, but since I would never have either of them quite that high in regular use I wasn't overly concerned.  At least not yet.  The Hi-Z input does sound pretty good to my ears, fairly thick and present.  Definitely better than my old Roland VM3100 and about the same as the Lexicon Ionix 422 (which was surprisingly good considering).  I haven't tried any of the other inputs yet, but I am eager to try a mic - Focusrite has a good reputation with preamps.
 
For latency, the lowest setting (1ms on the slider) gives me about 3ms input and 4.1ms output latency, for a total of 7.1ms roundtrip.   That's a good 5ms better than the Ionix' lowest settings.  I was able to load up Rapture, Novation Bass Station (love it) and Dimension Pro at that latency and just squeek by.  Once I added Zeta2 I had to increase latency to the next value, which gave me about 5ms input latency.  This was still very good for live playing and there wasn't a crackle or pop in sight.   Again, better driver performance than the Ionix.
 
I also loaded a fairly full project which previously forced me to use the Ionix' maximum latency setting (2048).   With the 18i6, about half way up the slider seemed work just fine.   And where the 50% CPU range would mean increasing latency with the Ionix, it's now about 70-75% with the 18i6.   And that extra 20% or so is very welcome in my book!
 
So far, so good...
 

Anyway, have fun with it. I know I've been enjoying mine immensely. Cheers!

 
Ditto!  As long as it continues to work as it has over the last 48 hours, I'm good. 
 
Of course... I also purchased a BCF2000 so my time right now is split between the two.  Fun stuff. 

Plugged in one of my low end condensers tonight. The sound was ridiculously clear. In fact it brought the mic out so much I noticed the true characteristics of it. I need a new mic. lol

Hi, keneds. The short answer would be yes. I think it's a great little box so far and I am quite happy I chose it.

The long answer (there always seems to be a looong answer with me doesn't there? lol) is, probably. I have only really been doing some very basic stuff with it so far. Who knows, the thing might die or catch fire or call me nasty names when I'm not around after a while but I haven't seen any reports of malfunctions online so that's probably unlikely. The other thing is the Quad Capture is supposed to be the superior device of the two in regards to latency and signal quality but not having a QC to compare it to I can't say for certain. I just took a quick look at the QC on the Roland site and it does not seem to have an optical/ADAT connector for expanding the inputs which I thought Seth had told me it did but he must have meant another unit. In fact it doesn't seem to have much of anything. There have also been reports of some of the Roland i/o drivers being a little wonky but that might be for older devices and I'm sure once they release the next round of drivers those issues will be solved. But IMO unless you REALLY need the ultra low latency I don't think that unit is a very thrifty decision at $270 (the 18i6 is $300). Maybe take a look at the other Roland stuff that does have the expansion options. I say this because if you are worried about inputs expansion is one way around it. Just use the unit as is for light everyday tracking and if you need to record a full band at some point you could probably rent a mic pre box. The Scarlett however DOES have one of these connectors which is cool. Also if your old interface has an optical OUT (it has to be out) you can supposedly use that as an expansion unit with the Scarlett. I'm not sure how well this works but there are a couple other people on here who've said they've done it with the Scarlett and Matt from Focusrite told me that it was indeed that simple. I'm gonna try it with my Layla 3g at some point to bring up my multi in/mic pre count to 4. Speaking of which one other thing to know about the 18i6 is if you intend to use more than the two multi ins on the Scarlett be aware that the other inputs are line ins only so you'll need a mixer, DI boxes or amps with line outs on them (I'm pretty sure that's how that works) and without an expansion box or using SPDIF connectors you only get 8 inputs. But that's enough to record a full drum kit or do bed tracks with a full band which is what pushed me over the top to buy it.

Anyway, if you read the thread and have been looking at other reviews and articles online about the 18i6 you probably know most of that stuff already but I figured I'd condense it down in one post. Basically if you can tolerate only getting about 12ms round trip latency (7ms for very low intensity tasks from stevec's description) I'd say it's a winner and the price can't be beat for what you get. The high Z sounds great. The mic pres sound great. The MixControl software is super easy to use and allows you do do all sorts of neat stuff. You get a bunch of plug ins as well as Ableton Live Lite and Novation BassStation and the customer support is awesome. The only complaints I have ever seen about this unit were in regards to their old drivers and that issue has been corrected as of the last couple driver/firmware updates which can be found on the Focusrite website.

Hope that helps. Cheers!

Hi, synkrotron. Thanks for the input. It sounds to me like you are actually getting quite good latency from the QC. The limitation sounds to be the laptop. That 1-9 setting is likely similar to the settings on my Scarlett (1-10 milliseconds and no I don't really know how that works into the final equation but that's how the 18i6 and MixControl software deals with buffer settings). So at a setting of what I am assuming is 4ms you are getting better roundtrip latency than I am with my setting at 2. If you had it on a more powerful desktop that could handle the extra CPU load at the 2ms setting it is likely you'd be getting something around 5-6ms roundtrip and at the 1ms setting you could be getting the 2-3 ms roundtrip latency that device seems to be capable of from hearing the Cakewalk/Roland dudes talk about it. I think it really depends on the system at that point. I could however be completely wrong (I usually am about the really fancy tech stuff... lol) but if you know someone with a super high powered desktop it might be interesting to check out. I myself am curious what kind of results you'll get from the QC in general (mic pres, high Z, line in signals, general mayhem, etc) so let us know how it's working out. Cheers!

Sorry for not coming back sooner. I was having a bit of a nightmare last night, experimenting with different buffer size settings, and adding more soft synth tracks to my current test project. I had got up to thirteen synth tracks, plus one audio track (just some guitar noodling). I then added an instance of Rapture and I also decided to play with the Step Sequencer (didn't have that in 6). My lappy crashed five times, and at one point I experienced the dreaded BSOD. I even tried increasing the buffer size, quite considerably, just in case I was pushing the system too hard. But it still crashed, and I eventually deleted the Rapture instance.

Funny thing is, the CPU meter didn't show any real strain on the system at all. One of the eight cores was operating at around 45% and the others were being tickled at around 10 ~ 15%. The memory commit was showing as 3gb and the disk performance was a lowly 0.1%, as I expected, as there is only one audio track.

I am going to create another test project, but with only one instance of Rapture, and see what happens.

Anyway, back onto the Q-C. I have put together quite a detailed description of my laptop, including all of the different audio device buffer sizes and associated latencies. Probably too much info actually... An interesting thing to note is that in my last post I said that I was getting a roundtrip of 11.9 milliseconds. When I was making a note of all the buffer settings and their latencies, that 11.9 milliseconds had reduced to 9.8 milliseconds, a difference of 2 milliseconds. The only thing that I can think of is that I realised yesterday that there was an updated driver available for the Q-C, so I duly updated it.

Regarding the other areas of interest, that is, mic pre's, hi-z, line input signals and stuff... I've yet to get onto that, but will do in the next couple of days. I'll be frank... I'm more of a synth person, and I don't do much real instrument recording for my own material. I do intend to address that, however, and I'll be incorporating more guitar into my compositions. I only hope that my fifty two year old ears can still tell if what I am listening to is any good :)

Here is all the gumf:-

Laptop Specification:-
CLEVO Model = P150EM
Chassis & Display = 15.6" Matte 95% Gamut LED Widescreen (1920x1080)
Processor (CPU) = Intel® Core™i7 Quad Core Mobile Processor i7-3820QM (2.70GHz) 8MB cache
Memory (RAM) = 16GB SAMSUNG 1600MHz SODIMM DDR3 MEMORY (2 x 8GB)
Graphics Card = NVIDIA® GeForce® GTX 675M - 2.0GB DDR5 Video RAM - DirectX® 11
1st Hard Disk = 120GB Intel® 520 SERIES SSD, SATA 6 Gb/s (upto 550MB/sR | 520MB/sW)
2nd Hard Disk = 240GB INTEL® 520 SERIES SSD, SATA 6 Gb/s (upto 550MB/sR | 520MB/sW)
Internal Sound Card = Intel 2 Channel High Definition Audio + MIC/Headphone Jack (REALTEK)
Network Facilities = GIGABIT LAN & WIRELESS INTEL® N130 802.11N (150Mbps) + BLUETOOTH
USB Options = 3 x USB 3.0 PORTS + 1 x USB 2.0 PORT AS STANDARD
Firewire = 1 X 1394a FIREWIRE PORT

Some more chipset info:-
ACPI x64 based PC
3rd Gen Intel® Core™ CPUs
Intel® HM77 Express Chipset
Intel® Xeon® processor E3-1200 v2

External Sound Card = Roland QUAD-CAPTURE UA-55

Device Settings and Latency:-

Buffer Size = 1 (0.7ms, 32 samples)
Input = 1.8ms, 80 samples
Output = 3.3ms, 145 samples
Roundtrip = 5.1ms, 225 samples

Buffer Size = 2 (1.1ms, 48 samples)
Input = 2.2ms, 96 samples
Output = 4.3ms, 191 samples
Roundtrip = 6.5ms, 287 samples

Buffer Size = 3 (1.5ms, 64 samples)
Input = 2.5ms, 112 samples
Output = 5.1ms, 224 samples
Roundtrip = 7.6ms, 336 samples

Buffer Size = 4 (2.2ms, 96 samples)
Input = 3.3ms, 144 samples
Output = 6.6ms, 290 samples
Roundtrip = 9.8ms, 434 samples

Buffer Size = 5 (2.9ms, 128 samples)
Input = 4.0ms, 176 samples
Output = 8.1ms, 356 samples
Roundtrip = 12.1ms, 532 samples

Buffer Size = 6 (5.8ms, 256 samples)
Input = 6.9ms, 304 samples
Output = 13.8ms, 610 samples
Roundtrip = 20.7ms, 914 samples

Buffer Size = 7 (11.6ms, 512 samples)
Input = 12.7ms, 560 samples
Output = 25.3ms, 1117 samples
Roundtrip = 38.0ms, 1677 samples

Buffer Size = 8 (23.2ms, 1024 samples)
Input = 24.3ms, 1072 samples
Output = 48.6ms, 2142 samples
Roundtrip = 72.9ms, 3214 samples

Buffer Size = 9 (46.4ms, 2048 samples)
Input = 47.5ms, 2096 samples
Output = 95.1ms, 4193 samples
Roundtrip = 142.6ms, 6289 samples



edit - on reading this through I realise that I should really take the whole of this into its own topic, assuming anyone thinks it is worthwhile... it just appears to totally take over Beeps original topic, apologies for that. I will edit this out if requested.

yeah, I think you're right Beep, that I should start a new thread, or even two. I need to do some more tests in a project with just one instance of Rapture, for starters, and if I continue to have issues than I will raise a thread, in the appropriate sub forum. I don't have the Filmscore pack, but I did pay £14.99 to upgrade from LE to a full license, so I would like to see it working properly.

I will probably post some of the above as a new thread in the hardware forum, so that prospective buyers of the QUAD-CAPTURE can pour over the number. And I still need to "review" its audio recording capabilities.

Regarding Audio Optimization... yeah... I did do that, but I am wondering if I should do it again, considering my recent problem, and the fact that I updated the QUAD-CAPTURE driver.