David Satz wrote:
That's about all I can say because of the limits of my test signals. OK,
I can say a few things in the more clear-cut cases:

- The ART "Tube MP" is grotesquely bad. By a considerable margin it had
the highest distortion, in its normal operating range, of any equipment
I tested. And the Aphex "Tubessence" preamp (model 107, not the 1100)
had second highest.

Open up the 107 and you'll find a pot in the middle of the RPA circuit.
That pot is preset at the factory for a particular THD level. You can
turn it up and down if you want more or less distortion.

- My better preamps (Millenia Media HV-3B, FMR "Real Nice Preamp", Grace
Lunatec V2 and V3, M Audio DMP3, Sonosax SX-M2, Symetrix SX-202, and a
dbx 760X modified by Jim Williams) all had low noise and distortion when
stimulated by this test signal, with small differences in favor of the
Millenia Media preamp. They had distinctly different distortion spectra,
but were more or less similar in the total amount of their distortion.

I can believe this. Now, what happens if you put a 1:1 transformer in
front of one of these? The transformer should be much more of a source
of distortion.

- The M Audio "Flying Calf" A/D converter, surprisingly, held its own
against far more expensive converters, while the D/A section of the
"Flying Cow" converter was not nearly as good--though my "Cow" is an
older model, and the chips (cow chips?) in their newer models have a
higher specification.

There are also some board layout changes too, which may make for a change in
stability.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."