在音频放大器应用领域，DSP （数字信号处理）技术日臻完善， 已经可以 完全取代真空管电路。 内容详见下面链接：
http://www.mitpressjournals.org/doi/pdf/10.1162/comj.2009.33.2.85
附一个博士论文：
http://cegt201.bradley.edu/projects/proj2003/dtubeamp/
By: James Siegle
Advisor: Dr. Thomas L. Stewart
Abstract
Solid-state technology may dominate the present electronics world, but vacuum tubes continue to hold influence in the guitar amplifier industry. The sound of a guitar playing through a vintage vacuum tube amplifier has become a standard for most guitarists. Unlike solid-state guitar amplifiers, vacuum tube amplifiers produce specific, disorted guitar sounds. The quality and amount of harmonic distortion in overdriven vacuum tube guitar amplifiers has been found to be pleasing to several musicians. This desirable effect has been termed "tube distortion." Even though vacuum tube designs for guitar amplifiers are characterized by their superior sound, their disadvantages include high cost, fragility, limited availability of components, high waste heat generation, and manufacturing inconsistencies in the tubes. The objective of this project is to reproduce the distinct harmonic distortion of a 1961 Fender Champ with a low-cost DSP and thus implement a guitar amplifier with tube distortion without the bulky and awkward features of a tube amplifier. Once the DSP-based design is completed for this small amplifier, the algorithm can be reconfigured for other vintage vacuum tube amplifiers.
