"Well, one searches the interface along with a low output dynamic MIC to see what they can do. What they can do on 500mA USB power. "
Not sure what you are saying there G? (Surprise! Surprise!) but if you are alluding to the 500mA power limit of USB 2.0 being a problem for AIs? Ain't so. Well, not a lot.
Take an AI with 2 mic/line/HZ ins and 2 more balanced line ins? You can make a VERY good mic pre that consumes around 12mA (1 dual IC +2 BJTs) Another chip gives you the line ins, say 8mA? That gives you 32mA. The supply rails will need to be up converted from 5 to say +&-15 so a 1:6 current boost, 192mA. Yes you have the CPU to power but likely DOWN converted by an SMPSU to 3.3V and phantom power*, H/P* juice and some ancillaries but it CAN be done under 500mA.
It is true that to get the ultimate in low noise and high headroom, mic pre amps have to use very low internal resistances and that means they pull more current but such devices are only a few dB better for noise than the better AIs. Then, AIs rarely deliver more than +12/+14dBu from their line outputs but they don't need to, +10dBu is more than enough to fully drive any active monitor I am aware of and most hit max SPL at 0dBu.
*This is where the compromises can show. +48V often has far less than the 10mA per channel proper spec' but then most modern capacitor mics need 2mA or less and I saw a spec for one very well specified mic (yeah, fergot!) that needed just 9V. Now, at that voltage I dare say ultimate SPL headroom would be limited but we is talking HOME recording! SPLs in excess of 100dB are not likely.
Headphone output is often puny on many AIs (many with Rat power!) but this is more a 'gain' thing than brute force.
OP: Gain specifications. Yes. There are..'Lies, damned lies and specifications!" Actually, giving a gain figure, XdB for a mic pre in an AI is not that helpful. What we REALLY need to know is 'X mV in for say -18dB FS' in the DAW. We know the approximate output of common mics (SM57/58 ~1mV at 90dBSPL) or we can quickly find it for most decent mics. NOW! Be aware. V old audio fart about to opine!
WAAAAAY back in the day we had (in UK) about 3 very decent magazines dealing with audio matters. Hardly an issue came out without someone taking a mnfctr to task (often a reviewer in the mag itself) for sloppy, badly written or incomplete specifications. The result was a general improvement in such specs. Often there would be a bit of a cow between mag and mnfctr as to what this or that meant. Great reading!
Today there are no such 'Spec Police' Some magazines do their best but the sheer scale of new kit pouring onto the market each month means they can never catch up, leave alone have the time to improve things...Fork! When was the last time you read of a 48V load test or one for monitor self noise?
OAF ceased.
Dave.
I'm a keyboard guy so it's pointless not to have. There are other ways but why muck w/that when I don't have to?
