soundwise between the two, i doubt there's anything in it that you'd notice particularly if you sat down and did a blind text with really expensive monitors in a controlled room. You might.... but even f you did, is it relevent... For example, Martin Walker at SoS uses an E-mu 1820m as his 'reference' card, and in one soundcard review he said when blind testing he could always tell his 'reference' e-mu cos it was 'warmer'.... However, warmer doesnt mean any more accurate, and all cards now even cheap ones like the m-audio Delta Audiophile 24/96 deliver flat audio out with sufficient dynamic range to be able to mix accurately if all other issues are also attended too (monitors/placement & room acoustics)
I own the 1820m myself, It's curently sitting on the side disconnected and un-used because to me, any subjective warmness is irrelevent, because first i need reliability and the e-mu in one mahine we use for film work doesnt seem to like it so much, and i dont have toime right now to investigate why, i need to WORK ('pro') so the e-mu is unused.... so... what is 'pro'
Instead, i used an old Hoontech (ST-Audio) dsp24/96 with the breakout box... subjectively not as 'good' a card (in terms of converters and perceived 'warmness' etc), and spec wise on paper the Hoontech is not such a good card/rack, however, it works, it's reliable, it doesnt crash and we can get on and do work for which professionaly we're getting paid... Now, we've used this cheap rack/card system now to mix 2 award winning films... is it profesisonal?.. yes, in that it got the work done... When we render off the tracks to go for Dolby mixing, IF they ask for 192k, we'll render it off at 192k (but they wont ask for that).. I know if i render off a 192k file, it's going to sound eq-wise pretty identical to a 44.1k file... The Dolby engineers will apply further Eq as required for their cinema mix so even the eq isnt 100% fixed, we need to supply them with flat files without any extreme eq so they can finaly balance it, and for audio CD work the same is true, you want to give the mastering engineer a fairly flat mix so they can eq/compress what they require.
More thoughts.... Rendering your project to various sample/bit rates also has nothing to do with the card, except if the card doesnt do 192k and you render off a 192k render the card cannot play it, but the actual render can still be done. However, if you mix at 96k and render off at 192k, again, you'll not see much difference in terms of anything you might alter in the mix... meaning 192k playback isnt suddently going to reveal potential mix issues you didn't hear at 96k or 48k, an overall mix eq curve will remain almost constant if you change sample rates.
Now, as to the word 'pro'... that's very subjective... 'Pro' I'm assuming means able to be used to make money, to do contract jobs, etc.... well, any of those items can do that. Unless you tender for a job to mix/convert masters to 192k spoecificaly and you cannot audition the results then no, the card wont be able to do the job, however the chance of you getting such work is miniscule, i never heard of anyone being asked to mix/convert material to 192k as a specific job task although i'm sure it happens somewhere... if you're NOT setting yourself up as a professional mastering service then it's probably irrelevent and may be irrelevent even if you do setup for that.
So, if we use a cheaper soundcard to mix pro film music that is deemed pro enuff so that it doesnt stop the film from winning awards, does that make it a 'pro' card... I say it does.
so cards are kinda often overtalked about... imo it's something which gets embedded in peoples minds due the preponderance of attention given to such stuff in magazine reviews - A reviewer has to come up with wordage so they talk about such things to fill lianes (after all what else can you say about a soundcard beyond "Its ounds good and didnt crash system we tried it on" - but because so much verbage is applied to sample rates & bitrates in terms of printing them, people see this and assume higher means better..... you end up with the situation of people assuming that somehow miniscule differences between soundcard is somehow going to make or break the 'quality' of their music which is utter nonsense. One of the best card for a super flat, ultra crisp analog sound is actualy the VERY old DAL CARD-D - it's ancient now, it was a well known card back in the mid 90's, but the sound is so crisp
My favourite soundcard right now is the cheap ESI JULI@, because it's elegant & simple, it's switchable from -10 un-balanced to +4 balanced with seperate converters for each, and is only 80 quid... It's quiet as a mouse and flat as a fart eq-wise, and that is all I require as long as it's reliable and co-habits with other hardware well and doesnt give problems and crashes.
anyways, as i say, i dont think you'll really see any great differences between these 2 items, you might under good conditions, but unless you use a properly balanced control room and top-end monitors, then the monitors themselves and the room will be adding far more in terms of subtle differences to the sound that the cards themselves and that's something you need to get used to and you'll need to work on your mixing in that room with those chosen speakers to acehive the best from that setup for a mix.
btw, the edirol FA-66:
"24 bit/96 kHz Full Duplex or up to 4 Channels with 24-bit/192kHz"
which means i assume, it's not full duplex at 192k meaning it's playback or record only at once, but yes you could use it to playback 192k files if rendered at that rate or recorded at that rate, BUT you cant multitrack with it at that rate (playback while recording)
hard call - 229 GBP for the edirol fa-66 with 6x6 in/out (but only actualy 4 analog outs and 4 analog in's (2 of those on phono unbalanced connectors) ... or 170 GBP for the hercules which has more in/outs (10x8 balanced + digital i/o)
so obviously, the hercules is the one to go for for multitracking if you want to record a backing drumset/bass/rhythm guitar or whatever, all at once with 10 inputs from a mixer for example. The Edirol is more a multimedia production-suite item with less i/o's but essentialy all the connections you need for a production studio which DOESN'T need to record many multiple inputs at once (ok for vocals etc and DAT transfer), but there's no wordclock which is odd for such an item.... Also the edirol has a connector which could be used for importing video footage for example from a camera - the Hercules DOES have wordclock tho, and also like the edirol has a standard 1394 firewire connectivity... you also get analog s/pdif on the hercules but only optical on the edirol as far as i can tell.
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