With regards to the links, as it happens, I totally agree that 15in Tannoy Reds struggle to handle complex music. The crossover is too simplistic and the cones too hard to control with a low power amp. Reds can be lovely in a simple vintage system but they don't quite qualify as hifi in my book. Golds are considerably better and work with modern 8 ohm amps (Reds and Silvers are 16 ohm), but an Ongaku - or almost any other kind of low-power SET, regardless of quality - is the wrong thing for them entirely. I know because I have tried it too, having owned 15in Golds for many years. (Not an Ongaku but a Jinro which is much the same thing, made available to mere mortals rather than the super-rich).
in my view the HPD (particularly the 12in HPD) is the best driver Tannoy ever made, never bettered even today. Lots of reasons for that but it is the ultimate expression of the Monitor series, before Tannoy's financial difficulties led them to start experimenting with plastic cones, cheaper magnets and the like. The expertise was progressively lost after that and never properly recovered.
I did have to laugh at your comment that 20w for Tannoys is 'not a good idea'. Ordinarily I'd agree with you on that, but it's not the whole story. I've been running Tannoys since I bought my first pair with what was effectively my first pay cheque after graduation in the mid-1980s. I've owned them ever since in all sorts of sizes - I've owned Autographs, two kinds of Lockwoods, original Lancasters, Chatsworths, Cheviots, GRFs, and various custom cabinets. My current speakers were a collaboration with Paul Coupe of RFC Audio (probably the top guy out there working with vintage Tannoys) and built to my requirements. I've had more than 40 amps through here, driving these speakers (actually closer to 50 when I go through my list), everything from Chinese cheapies to £60,000 Kronzillas, 3w 2A3 SET to 400w Class D, and all sorts in between, Class A sand amps, Class A valves of various sorts, OTL, chunky AB push pull pentodes, Kondo, AN-UK, Shindo, Leben, ARC, EAR, Pass, C-J, Berning - you name it, it's been here.
My experience is predominantly with vintage Tannoys but on another forum I do belong to a circle of people within which are several who either currently or have previously (before going vintage) had the modern Prestige series so I've heard most of the current models too. I have a soft spot for the modern Canterbury but in my view it's not quite at the level of the vintage drivers.
The big paper cone and the peculiarities of the Tannoy approach to crossovers mean that regardless of the specific model, they are an unusual speaker. They generally need a decent damping factor, but not too much - something 20-50 is normally the ideal (high power solid state in my experience gives you grip but sucks the music out of them - though some way well prefer things that way). For Tannoys generally, 25w of push pull valves will work better in my experience than high power solid state, but there's a point after which even too much valve power is not required. In general, my experience is that single ended amps, valve or solid state, struggle to control the cone. My preferred amp for a long time (about 4-5 years) was a Radford STA100, push-pull KT88. From all my amplifier experience with Tannoys I had come to the conclusion that this was the optimal setup for Tannoys.
Consequently, my current Silvercore 833C SET amps, purchased less than a year ago, were a shock. I tried them out of curiosity as part of my regular auditioning, but being 20w SET I did not expect them to control the Tannoy cones adequately. Indeed at the very margin of bass control they do not have quite the grip of Radford or EAR 100w push pull pentodes, but in every other respect the sound is considerably improved - timbre, presentation of acoustic space, musical communication, naturalism of high frequencies. I think it has something do with the unique power supply arrangement - 2 x 10A at 10V produced by its twin switching power supplies in each monoblock - and the pentode driver stage which uses the ultra-musical EL34. Whatver is the secret sauce, they do not suffer the limitations exhibited by the vast majority of single ended amps driving Tannoys (including Ongaku, Kronzilla and the like). I tried to engage their creator in a conversation about why this might be but he wasn't interested in discussing the design, which I think is unfortunate. I would love to grow my knowledge in this area.
Romy's wet cat analogy is fun and like all generalisations, it has some points of truthfulness but can never be the whole story. I have a deep suspicion of grand ideologies, systems of everything, whether we are talking religion, politics, institutions, or anything to do with art. Systems or models are never complete and there is always room for surprise. Dogmatism is as unwelcome in hifi as it is anywhere else. Actually my experience with Tannoys and Silvercore SET - I am on record elsewhere with a conclusion based on experience that 20w minimum push pull is required to get a proper sound from Golds, double that for HPDs - reminded me once again that there are no absolutes. We are all simply on a journey of exploration. It's something you might want to take into consideration when you comment too.
Anyway my maxim is: beware of hifi salesmen (or self-appointed 'experts' of any sort) who pretend (or perhaps even believe) they know
it all - they are talking bollocks and such behavior immediately casts suspicion on anything at all that they have to say.