Ralph, any downside to source switching with CMOS electronic switches instead of relays?
Yes- there is a reason we still use mechanical switches. CMOS is pretty good- but have a higher resistance and more diode effect than actual switches.
I didn't listen to it very critically when I realized right away that it
didn't sound completely transparent. I want to say maybe a tad less
dynamic but YMMV. My feeling is that a preamp or anything that is
introduced to a signal can only degrade it so I wasn't completely
surprised. I even think a switch box wont be as good as without anything
but the degradation may not be noticeable to me. I think a preamp that
"improves" the sound just means that it added some colouration and/or
minimized some faults to the source signal so that it sounded nicer to
the reviewer. I'm sure my taste for tube sound is nothing like what the
source really sounds like without any colouration. My 2 cents.
Its a lot more complicated than that! And I'm only going to put this in a nutshell:
The reason we are able to have a hifi industry is due to the ear's masking principle. The ear is keenly sensitive to higher ordered harmonics which are made by *all* electronics. Tubes tend to make more harmonic distortion in this regard, but because they also have either a 2nd or 3rd harmonic (which is substantially less with solid state), that particular distortion is able to mask the higher ordered harmonics. This is why tubes sound smoother than solid state. Solid state makes these lower harmonics also, but not as much, so they are unable to mask the higher orders *as much*.
The odd thing is that the injection of a 2nd or 3rd harmonic also allows the ear to hear better lower level detail and increased soundstage width and depth! This is why tubes generally are more detailed and have better soundstage. However, the ear also interprets distortion as tonality; if the tube electronics have *too much* of these lower orders, it can sound more 'romantic' or 'rich' than is reality. So a designer has a fine line to walk- too much distortion and the gear is 'colored'; not enough and the gear is bright and harsh.
The bottom line is we can't make amps and preamps that don't make distortion. So this masking principle is important- without it hifi would not exist.
Passive systems OTOH have their own issues- they effectively raise the output impedance of any source (as far as the power amp is concerned) and this seems to be why impact is impaired. They can also cause high frequency rolloff; even though that rolloff and be ultrasonic, the phase shift that can be introduced is interpreted by the ear as a rolloff. To prevent this, the interaction of the control and the associated capacitances (interconnect cables) has to result in a rolloff above 200KHz.
For these reasons, a tube preamp, if designed correctly, can often sound considerably more neutral with greater low level resolution than a passive or active solid state system.
