My FF400 arrived today and I have been playing. I'm very impressed with it - in fact, I'm over the moon. All my concerns further up the thread have been met positively.
I have been conducting some comparisons between the FF400 and the MH ULN-2 (a friend owns one on a mac) and first thoughts are that the FF400 stacks up very well indeed, and thats not factoring in the price difference.
Put simply the sound quality of the FF400 is excellent. Very detailed, crystal clear with effortless and smooth delivery even in the most busy music. The control software is a breeze and my worries about connecting it directly up to high end powered monitors are unfounded. I have a small issue with my FF; for some reason input 4 has a higher noise floor than all the other inputs according to TotalMix. When I increase the gain on inputs 3+4 the noise floor difference between inputs 3 and 4 increases as the gain increases. I think there's a noisy analog circuit on input 4 of my unit.
When I've conducted some more thorough tests comparing the MH and the FF, I will post back my thoughts (comparisons so far have been with different monitors, which hardly makes a fair comparison possible). The only tiny thing I miss on the FF is a level VU for a stereo pair - it's a bit disconcerting not knowing visually what's going out to your monitors. Totalmix tells you this, but I'd like it on the front panel of the unit.
To sum up, my advice would be to get the 400 unless you need the extra I/O and pres of the 800. Sonically, I expect the units will be so similar that the differences are negligible - RME have said that, and so have others (people I know) who've compared both units closely.
@Zeuwi..
With regard to compressors, if you're recording at 24/96 or even 24/48, there's no need to worry about using a compressor on the analog side (ie. before the FF). There's so much headroom, just leave the levels fairly low to handle the wide dynamics of the mic then use your favourite software compression in your DAW (my personal favourites are the URS EQs and dynamics right now). You'll lose nothing in quality; in fact you'll gain quality, since there will be no analog makeup gain you'll get a much lower noise floor from your mic.
The FF400/800 have no inserts but plenty of IO and internal routing possibilities.
Would you run out of connections? That's a tough one for anyone to answer but you. You have 8 analog ins and outs on the 400, which can be mixed with up to 16 channels from the PC. In reality, you will be mixing in your DAW down to stereo which will only use 2 channels in the FF. You could mix your outboard in with that or route the inputs back to the DAW for recording. I don't know if its possible to route the entire FF mix back to the PC for recording yet, thought you'd probably want to record all your inputs into the DAW for further processing and mixing in the DAW. In short: 8 analog ins + 8 adat ins + 2 spdif = up to 18 ins. Most outboard outputs stereo so assume you will need 2 inputs per outboard.
The amount of tracks you use in the DAW does not affect the firewire bandwidth because the tracks are mixed down to stereo before being sent to the FF. Firewire bandwidth becomes an issue if you're recording lots of inputs simultaneously, or using more outputs than 2 from the PC. Take a look at the FF manual (on RME's site) for more info about what you can expect from the FF400 in terms of firewire limitations.
I don't really see much point in using external D/A. The FF400's DA is really very good and although there is better you will be paying for the privilege. In
this thread there's a comparison of the FF800 against the Rosetta 800 and the poster reports that the Rosetta's DA output stage is better than the FF but in terms of AD and inputs the units seem to be very similar; to my ears the FF800 is actually better.
Early days yet, but I can highly recommend the FF400 both sonically and in terms of stability and usability too.
z.