Katfnc, you make a very good point in your post just above. And in looking further at the descriptions of the two preamps it appears to me that you would be at least as safe with the VTL as you are with the Spectral, regardless of how effective or ineffective the DC protection mechanism in the amplifier may be.
The VTL design includes coupling capacitors at its outputs, even though its output stage is apparently solid state, as well as coupling capacitors in its internal signal path for the tube stages. Those will block any DC that may originate in the preamp or the CD player (or in any other source component).
In addition to providing protection against DC, the Spectral preamp is described as providing protection against oscillation. But I would feel certain that the VTL requires no such protection, due to its much lower and more conventional bandwidth, and the fact that it uses zero global feedback and very minimal (less than 2 db) local feedback. The Spectral’s description does mention the use of feedback (although not quantitatively), and of course as is typical of Spectral designs it has ultra-wide bandwidth. So the reason it provides protection against the possibility of oscillation is that it needs it.
Regarding Spectral’s email address, it’s strange that their website provides neither that or a means of contacting them directly via the site. But I found elsewhere that their email address is, or at least has been, spectral@prodigy.net.
Best regards,
-- Al
