I owned two of the amps in the article-Harman Kardon Citation II, Dynaco Stereo 70. Compared to the amps I have now ARC, Unison, they are euphonic and transients are slower. They were also lacking in top end, but so were the speakers that were made during this period.
@wharfy Neither of those two amps above have a rolled off high end but apparently your speakers did. The HK had full power bandwidth well past 50KHz; the designer was big on bandwidth. The ST70 does quite well in that department too.