+1 Mapman.
As I’ve said in a number of threads here in the past, the main usefulness of specs and especially JA’s uniquely comprehensive measurements is in identifying and **ruling out** candidates for purchase that would be poor matches with other components in the system (e.g., due to impedance incompatibilities, mismatches of gains, sensitivities, power capability, etc.), or with the listener’s requirements (e.g., peak volume capability, perhaps deep bass extension, etc). But not in selecting among candidates which make that cut, where listening is essential.
By doing that preliminary screening based on specs and measurements, the randomness of the selection process is decreased considerably, as is the likelihood of expensive mistakes.
A second major usefulness of specs and measurements is in diagnosing problems or sonic issues that may arise or become apparent in a system that has already been assembled.
As evidence of these usefulnesses of specs and measurements, I couldn’t begin to count the number of threads here in which I and many others have found it useful and in fact necessary to refer to the measurements JA provides in Stereophile. Where else is one likely to find, for example, the output impedance at 20 Hz of a tube-based line-level component, which is essential information in determining impedance compatibility with solid state equipment that it may be asked to drive. Where else is one likely to find how a speaker’s impedance varies as a function of frequency, which is not only important information in determining how much amplifier power is required, but can often be helpful in predicting whether a tube amp or a solid state amp would be the best choice for the particular speaker, or if both kinds of amps might be suitable. And where else can one find a **meaningful** indication of speaker sensitivity, rather than a manufacturer’s spec that may be optimistic by several db by virtue of clever but misleading "specmanship." For example, by basing the spec on whatever frequency produces the best number, as I’ve seen done in a number of cases, or by fudging the number in some other manner.
Finally, it is also sometimes possible to rule out candidates from consideration on the basis that some of their specs or measurements are simply TOO GOOD. A classic example being Total Harmonic Distortion numbers that are extremely small fractions of 1%, which depending on other aspects of the amp’s design can be indicative of heavy-handed application of feedback, the likely result being Transient Intermodulation Distortion and excessive amounts of the most objectionable kinds of harmonic distortion.
Best regards,
-- Al
