He was a very good writer no one argued that and started off as you suggest but he went past being a reviewer and made himself the maven and brought a lot of politics into the business. My comments on what I saw heard at his place remain. Point was he didn’t just review he made it up and gave false guidance.
I read early TAS and treasured my back issues until around '96 when The Great Flood in my basement destroyed my collection. HP was indeed an entertaining and influential writer.
The story goes that he started TAS in reaction to how dissapointed he was after purchasing one the most touted speakers of the 1970s - the Bose 901.
Where I give him credit is in three areas:
1) HP promoted the idea of subjective evaluation of audio components and systems.
Listening well and describing in some detail how a component sounded and comparing components based on their sound was a reaction to the then dominant Julian Hirsch / Stereo Review approach of gauging an amplifier primarily by its circuit construction and electrical parameters - so many (all ?) products received wonderful reviews from Hirsch. Hirsch: “I do not believe that any amplifier that is reasonably good and operating as intended has any sound quality of its own, at least not in the sense that phono cartridges, speakers, and listening rooms have their distinctive sounds.”
Some will tell you the popularity of those Bose 901s came from two sources: Bose's advertising and Hirsch's 1968 review in HiFi Stereo Review. Hirsch: "I must say that I have never heard a speaker system in my own home which could surpass, or even equal, the Bose 901 for overall “realism” of sound."
To describe a component's sound Pearson adopted/created concepts and vocabulary that his readers reacted to positively; they related to his writing because they could hear what he described in their own stereos. And if they did not, they attempted to make changes to emulate what he described. Imo his writing about psychoacoustic properties (soundstage, depth, etc.) and how those tied into speaker setup and room acoustics were among his more innovative articles. Pearson heard amplifiers sounded different from one another, Hirsch did not. HP was an early promoter that wires can sound different from one another.
2) He named his audio journal,'The Absolute Sound' after what he claimed was his reference point for subjective reviewing. The absolute sound is the sound of live acoustic music.
At least he had an ostensively definable reference point - the sound of live music, not organic oranges. To bolster his credentials, HP talked a lot about attending live music events and sometimes described what he heard at a concert. Thougn not new, Pearson made it seem as if it was a different approach. A reference that is not a recording or another stereo system.
3) The early TAS was subscriber funded as far as we know. That led to a somewhat sketchy publishing schedule but the absence of advertising lent credibility to the publication. No payola for featuring certain products or writing favorable review results. No advertisers allowed him and his writers to do what today's audio magazine shy away from and that is shootouts among multiple products in a single review. Readers love shootouts.
But ... in my opinion
HP eventually could not stay true to his notion of the absolute sound. He did not develop a consistent vocabulary to describe live acoustic music that he then could apply to what he heard from a stereo. His vocabulary was largely based on the sound of music reproduction and he did not have a feedback loop to the concert hall to inform or validate it. Nonethess Pearson became - or was made into by his readers - the venerated maven he is seen as today. His vocabulary and language highly influenced several generations of audio writers and today the world of audio writing and reviewing sometimes feels like it operates within a self-proscribed naval gazing bubble. How many people here - admittedly armchair critics - say too many reviews sound the same. Some of this was Roy's target.
TAS eventually accepted advertising in order to expand and establish regularity. At first all ads were relegated to the back of the magazine, not interspersed with reviews. Eventually the format changed from journal to glossy - bigger pages with ads everywhere. Iirc at first an ad for a product with a review was not allowed in the same issue as the review; now the review and the ad are within a page or two of each other. This has created the most frequent criticism I hear of audio magazines - the possibility of pay for positive review - I know it is not true, not at least for myself, although the placement of ads and reviews is not in the hands of the writers.
Is that too harsh? I hope not though I have paid a price for critiquing the industry in which I participate. While sometimes molds are difficult to work free from, I do believe audio writers have positive intent.