Quad, who refused to play by the 1980s magazine and dealer rules, had quite an interesting tone control system on the 44 and 34 preamps. The key bit being a ‘tilt’ control which shifts the whole balance around a pivot point at I think 1kHz or so. That is used in conjunction with a more conventional bass cut/boost and two HF filters. Some clever thinking that I imagine some would find useful, though I very seldom used it as it was a bit of a faff just to blunt an overly bright CD or whatever (I did use the filter for that now and again).
The problem with the ‘tilt’ for me was the very few times I ever even think of wanting tone controls is to dull an unusually fierce digital recording (I usually just get rid of the CD and find a better mastering) or to cut bass on hyped-up ‘small speaker mix’ pop, rap etc which is just overpowering through 15” Tannoys. The tilt alone was useless for this as cutting the top boosted the bass and vice-versa, so it always involved actually EQing using the three controls in unison, which was a real faff. This exacerbated by the beautiful stepped attenuators which for me had too large steps, i.e. I always felt it was ‘too little’ vs. ‘too much’ and would have preferred only to have a click detent for ‘off’.
Since I’ve retired the 34 for a valve pre I haven’t missed this functionality in the slightest, though I do have some CDs (mainly rap etc) that I only play upstairs as the bass is so boosted up for tiny modern speakers or headphones and I have no ‘cut’ on the Tannoys.