restorer-john
Grand Contributor
Only purists hated tone controls and wanted defeat buttons so the market gave it to them.
Tone controls were originally removed or bypassed not for purists, but for the elimination of frequency respones variations, lowering of noise and distortion and better channel balance in preamps and integrated amps. All those parameters were easily measureable and highly obvious. Manufacturers were striving to produce the best products for their spec sheets. The S/N differences between active tone controls at 0dB and bypassed is a number of dB. Scrap the entire active front end tone/buffer and go direct to a higher gain power stage and get even better numbers.
In the late 70s- early 80s, many audiophiles realized they rarely or never used their tone controls and the British cottage HiFi industry saw an opportunity to save a heap of money, drop the unwanted controls, proclaim them as polluting and not pure, whether they were bypassed or not. The Audiophools jumped on board and soon even the loudness contour was deemed evil by the British HiFi press. Filters were work of the devil too. Bad luck if you played vinyl- the infrasonic filter was disappearing in the rush to rid gear of useful functionality.
By the early 1980s, most integrated amplifiers from the big manufacturers had direct/bypass buttons that basically put a volume pot in front of the power stage. S/N ratios were above 110dB with respect to 65W amps. Things were looking good, just as CD came along. It was so "pure" you needed nothing between your player and your power amp- even preamps were getting banished. Manufacturers put CD-direct inputs as additional inputs on power amps.
My preamplifiers are run in direct pretty much 99% of the time. But all my preamps have tone controls, filters, MM/MC stages etc. The presense of those useful functions in no way impedes the performance when in pure/bypass/direct.