Mpffff.... Speakers are difficult loads altogether. Amplifiers treat them all pretty much the same within their design parameters. Well made amplifiers designed against this sort of thing will pretty much sound all the same within their performance limitations all other things being equal. Amplifiers are what they are, and what they do is pretty basic and pretty simple. To the extent that they do it without adding or deleting artifacts from the original signal, they are successful. Speakers are what they are, and far less basic and far less simple. And they absolutely CANNOT sound like the original signal. They can get reasonably close but like Achilles, never quite there. If I have to get out the rubber mallet, I would define the issue as follows:
Take a _very_ difficult speaker for loading - the original issue AR9. A nominal 4-ohm speaker that drops well below 1 ohm at certain points. I know that, certainly. However, any two given well-designed solid-state or tube amps operated within their performance capacities (not driven overly to clipping) will pretty much sound the same driving _those_ speakers. As they are both facing the same load and both doing the same thing with the same source. Amplifier stability into such loads is critical - but again, well within easily achieved design limits.
A well designed amplifier will both have a sufficiently rugged power-supply without considering capacitance (other than for smoothing) on-board to handle their RMS rating all day and all night. And *should* (hence the term 'well-designed') be able to handle at least a 20dB peak from on-board capacitance, with a 30dB peak not being out of the question. My only-mildly tweaked Dynaco ST120 can do that - and that is perhaps the least capable of my amps.
However it is sliced-and-diced, starting about 1970 and getting more and more so to today, electronics have become more-or-less commodity items with excellent performance achievable using standard technology and standard components and conventional designs. Whether tube or solid-state, the primary differences between them outside of the Crap Zone are in sheet metal, eyewash and quality of peripheral items such as controls and jacks. That there is an entire segment of the industry dedicated to making its victims - err - customers think differently does not make it so. Hence my reference to differentiating between what isn't there, and how it applies to revealed religion. That is much like the difference between a hippopotamus (Behemoth - to the biblical). That very nearly totally transparent amplifiers with very high power may be had at 1970-equivalent prices of $50 absolutely terrifies the high-end audio industry. And they have their propaganda machine running at full speed to "say it ain't so".
You do need to read for content. I used Patrick Turner's amps as an example of _WHY_ separate power-supplies with complex umbilicals may be necessary. And, for the record, when dealing with perhaps 100kg + of electronics, such separation becomes at least convenient if not necessary. And given the success of those items it follows also that there is no electrical reason not to do it. And it also follows that, again with proper design considerations, there is neither danger nor degredation of sound by doing it. I took you for valve-challenged as you seemed to think that weight was not a valid issue. Unless one is into OTL designs - again, another discussion, only this one over beer-and-chips (crisps to you) as OTL is for cheapskates - high-power tube amps (50 watts or more) get heavy, and that weight increases on a sharp curve as power increases - not a linear relationship. Consider a 150-watt tube amp - and the weight will be in the 80 (35+kg) pound per channel range.
For the ultimate heresy - I take the position that tubes are much like vinyl. Enjoyable dinosaurs of which very nearly every other possible medium or device is better. Except that... And it is those 'except thats' that keep me in the hobby and constantly experimenting with it. I have enough core electronics (tube and solid state) to operate eight (8) systems - five of which are active at this time. But I have at least 15 tuners, 12 sets of speakers, 6 phono cartridges with two more planned (the Rabco ST-series is excellent for easy cartridge switching), and three active turntables. Not to mention various CD players, cassette & RtR devices and so forth. Most of which were acquired in some state from less-than-perfect to random-parts-in-a-bag. Swapping out electronics makes near-as-no-difference most of the time (again, I would not pretend that the Dynaco ST-35 will sound the same as the Citation 16). Swapping out transducers, tuners and tape machines - yes, there are LOTS of differences there.
Sorry for being long-winded - but there it is.
Peter Wieck
Melrose Park, PA
I've designed, built and still use 150W + 150W rms valve monoblocks. But not exclusively, I also use SS amps.