Here's a link which discusses the difference between tubes and solid
state for recording preamps:
http://www.dwfearn.com/tvst1.htm
Here's the abstract of the article:
Engineers and musicians have long debated the question of tube
sound versus transistor sound. Previous attempts to measure this
difference have always assumed linear operation of the test
amplifier. This conventional method of frequency response,
distortion, and noise measurement has shown that no significant
difference exists. This paper, however, points out that
amplifiers are often severely overloaded by signal transients
(THD 30%). Under this condition there is a major difference in
the harmonic distortion components of the amplified signal, with
tubes, transistors, and operational amplifiers separating into
distinct groups.
--
Fred Gilham
....every candid Reader will easily understand my Discourse to be
intended only in Defence of *nominal* Christianity, the other having
been for some time wholly laid aside by general Consent, as utterly
inconsistent with all our present Schemes of Wealth and Power.
--- Jonathan Swift