In article , Bob Latham
Jim, I remember you did some tests on one these devices and wrote it up
some time ago. Was the one you tested the 2nd generation one with 192/24
IIRC The Focusrite 2i2 I tested maxes at 96k/24 bit. If there is a '2nd
generation' 2i2 then I didn't have that so can't comment on it.
I have tested other devices that will capture 192k/24, but note that -
unsurprisingly - the cost rises!
The above shows the results I got from the types I suspect most people will
use, inc. the 2i2 which I thought the best of the bunch. I regard these as
general consumer/musician grade. They can work nicely in simple situations
if used with care
Shows the more expensive ADCs I tested. Of these I preferred the Benchmark
ADC1. This will record at 192k/24, but its USB interface is limited to
96k/24 because they made it USB Audio Class 1 compliant. It is aimed at
studio use where at the time Windows required a driver for Class 2. However
I think the later Benchmark models are now switchable Class 1/2 and thus
can do 192k/24 via USB. But I'm happy with 96k/24 as all I'm doing is
making transfers from old LPs, tapes, etc. 
Frankly, I thought the performance of the benchmark in terms of noise, THD,
etc, are its key advantages. I doubt anyone outside of a pro studio in very
special cases will actually need 192k/24. Most mics, etc, won't produce
anything that needs it.
The Benchmark ADCs allow the user to have *three* digital outputs - via
different interfaces *and rates* in parallel. So you can capture to a
backup CD, USB, and a recorder that can take 192k, all at the same time. It
also have very precise level controls and a useful set of indicators.
Studio grade. But costs much more that something like the 2i2. So if you
want good kit I'd say look at the Benchmark range.
Is there a means of using a better power supply or isn't that necessary.
I did find that the 2i2 and other USB powered interfaces could pick up
rubbish from the USB power line. Use with a battery laptop or a well chosen
mains-powered external USB hub may thus reduce this. The challenge is then
to find a good hub and its PSU. Alas, this is a matter of experiment as the
makers aren't likely to specify this.
 FWIW For a good DAC I'd recommend the Benchmark DAC3 range. Again,
studio / pro grade results, but costs. USB Class 1/2, goes to 192k/24.
Unlike some alternatives allows a good margin for intersample 'overs'.
Handy for clipped material.
Please use the address on the audiomisc page if you wish to email me.
Audio Misc http://www.audiomisc.co.uk/index.html