Have you moved away from full range to standmount speakers + subs?

@douglas_schroeder --

... Better big tower speakers make nearly all bookshelf/monitor speakers sound wanting, especially if they do not have a subwoofer(s) associated. One of the most telling characteristics of larger speakers is their ability to create a sense of scale that smaller speakers cannot.

I very much agree on the above, but below quoted sentiment of yours strikes me as peculiarly "heated."

I use the Legacy Audio i.V4 Ultra Amplifier following the review at Dagogo.com on all speakers, even the very efficient PureAudioProject Quintet15 Horn (reviewed). You bet I put 600wpc on that speaker because it seems like a completely different experience than some pissy 100W tube amp. I have zero interest in such pathetic amplification, which is also noisier than the Legacy amp. Want a downgraded experience? Feel free to go that route. Lower power tube lovers think they’re genius, but they are hearing insipid sound. Whatever.

Sufficient amp power, not only as a measure of stated wattage, is very much dependent on overall speaker load and not least efficiency. Take +100dB all-horn speakers, 16 ohm load and relatively benign phase angle behavior even, and 15 watts + brute power supply SET's can make 'em sound beastly and beautiful indeed. Subs I'd pair with powerful high wattage SS amps in any case.  

I'm very much for the importance of headroom and amps being less affected by speaker load, also saying that on principle I don't disagree with you on the importance of having (more than) enough amp power at hand, but make your setup an active one and the relative importance of amp quality is somewhat lessened seeing directly into into each driver segment without the interference of a passive cross-over. Practically speaking this (i.e.: passive configuration) is, in my mind, the foremost reason for amps sounding different, and close to the only thing that partially validates ridiculously over-build amps costing upwards of smaller houses. 

My own fully actively driven speaker setup has more than 2,5kW in total (divided over 3 amps) with a speaker sensitivity ranging from 97dB to 111dB's, by no means anemic, but I've heard low SET-powered and passively configured all-horn setups sounding anything but malnourished as well, so I guess it goes to show.  

@jjss49 --

Good insights. 

It seems to me though you're leaving out one scenario, namely that pairing the larger full-range speaker (in your case the Spendor SP100 R2's) with a pair of subs. Have you tried out that combination with the REL's of yours?

This is my own preference and actual speaker setup; large floor standing (semi-)full range main speakers coupled to a pair of large (20 cf. volume per cab) tapped horn subs. That's a total of four 15" drivers covering the range of roughly 85 to 600Hz, and two tapped horn-loaded 15" drivers (effectively adding up to the equivalence of four to five 15" drivers in air displacement area) reproducing ~20 to 85Hz. Whilst my main speakers are not full-range strictly speaking (35-40Hz is their lower, stand-alone limit) what matters is that four 15" (high efficiency) drivers are used in outlined region and what this means for the reproduction of this vital frequency spectrum. Important also is that they're high-passed below ~85Hz, meaning they are relieved of LF which cleans up their used range and adds further headroom. 

To my ears nothing beats large main speakers coupled to a pair of large subs. This combination alone leaves many variations to be explored though to fit many different needs and goals. 

@audition__audio --

Will get back with a reply tomorrow. 

@audition__audio --

Speakers are not limited by cabinet size! If you give the proper amount of enclosure for a driver, an increase in cabinet size is always a negative. Unless of course you want to listen to the baffle and cabinet specific distortions. Some of the nonsense written on this site from so called experts is astonishing. In a perfect world all you want to hear is the driver itself and I would like for someone to explain to me how it could be any other way.

We're not living in a "perfect world," so obviously it's a matter of weighing out compromises to aid the end result. Per your logic a larger box speaker (i.e.: bigger drivers and therefore bigger enclosures,) is less desirable because the practical scenario dictates that a larger enclosure resonates more, unless of course it's so heavily damped that its total mass equates several hundred kg's or even upwards a ton. There's some merit to this observation, but my counter reply would be: how much matters, to whom and not least relative to other design factors? It seems you pay little to no attention to the gains of going large (and more efficient), and instead place all your efforts on striving for total enclosure inertness and thus smaller size and lower efficiency - certainly if you plan on maintaining LF-extension and avoiding the hassle of tackling super heavy speakers. As an example: direct radiating drivers of subs of limited size and numbers will readily and quite easily reveal mechanical noises produced by the driver, which is distortion. How's that even if placed in a cab weighing close to a grand piano? There's loads of energy in the lower frequencies, and what you don't want is hearing the driver working or making an effort; this, by far, is the predominant issue in (U)LF reproduction, if you ask me, and not (large) enclosure resonances. The thing is though you have to hear the difference to appreciate what headroom is about, but I suppose it's a comforting tale to the audiophile that what's large is, by default, inconvenient - even undesirable - as a masking for what comes down to spousal demands, family obligations, prejudice, and the wants for interior decoration. It's HiFi in a nutshell, really: not seeing the forest for the trees. .