A lot! The current status quo:
As it stands, my present rig has stabilized enough to issue an update on this particular realsizing adventure. The $2,800 Zu Druids and $2,500 matching sub have been -- gasp -- upgraded to the $9,000 Definitions. Though seemingly going counter to the stated objective, considering that this 4' tall, 1 foot-squared speaker replaces $20,970/pr horns with active subwoofers, this still nets a 50% savings. The Duos present detail in a more obvious fashion and also focus the sonic imagery stronger, something I relate to the deliberately curtailed dispersion of spherical horns and how they couple to the air.
The Definitions counter with more top-to-bottom coherence, an even more immediate midrange, higher image density and superior bass (which, considering how accomplished the Duos are in that regard, is no mean feat). While the Definitions are smoother and more resolved than the Druids, the Duos seem more resolved again. The Definitions appear to soundstage better which could partially be a psychological factor. They're narrower and shorter to take up less common space with the virtual performers.
At 101dB (Definition) versus 103dB (Duos), either speaker allows for not only low-powered but affordable amplifiers. Though I didn't attend it, the recent Zu demo in Los Angeles had someone in the audience bring his 5wpc Almarro SEP. It soon stood in for Zu's mighty Rogue Audio Zeus. While commentators on the boards granted the Zeus certain advantages, the puny Almarro held its own and added certain performance aspects on its end, enough to apparently not have anyone in a hurry to return to the Rogue. Mind you, this was a sizable hotel suite of approximately 30' x 20' and high ceilings. Low power and loudness are not at cross purposes when you're playing in these sensitivity leagues.
While it may appear lopsided to mate an $800 amp to $9,000/pr speakers, the sonic results make a very compelling argument in its favor. The Decware Zen Taboo is another excellent match for the Definitions and in fact seems to prefer their 6-ohm impedance (the result of two paralleled 12-ohm drivers) over the Druids' which is twice as high. The $2,000 FirstWatt current-source amps are dead ringers for the Definitions as well and create a new benchmark for completely absentee noise floors. My favorite amp on the Zus since my Audiopax Model 88s sold -- and no, none have eclipsed 'em yet nor do I realistically expect that in the price ranges I'm exploring -- is the $1,800 50wpc AudioSector Patek SE. Its four trump cards are dynamics, image density, speed and minor warmth. It runs cool; is designed to remain powered up; and eliminates tube drift, tube aging and possible valve-related downtimes. As an extra bonus, it self-protects against dead shorts and other potentially catastrophic mishaps to make the term reliable cement-slab solid.
The $2,200 ModWright SWL 9.0SE is a keeper that seamlessly locks with the Patek SE to throw some valve-derived soundstaging and texture magic into the mix. Besides the sonics, I really enjoy the remote convenience as well. Cables include the Zu Ibis on the Definitions and what, to date, remains ludicrous overkill - two Stealth Audio Indra interconnects. As the opportunities arise, I will experiment with options that, hopefully, will come in around $500/pr ea. to make more balanced mates to the ModWright and AudioSector pieces. Crystal Cable power cords are thin, flexible, friendly and do the job as well or better than some of the engorged snakes.
Where all inhibitions are off is with the mighty Zanden Audio digital separates. Those -- ayee -- currently clock in at $43,440. You could argue with little effort how their presence here is utterly unreasonable. I wouldn't bother to disagree. It's an argument I couldn't possible win. Thankfully, I don't have to. Still, what's lost at the source can't be regained later remains valid no matter how disproportionally you decide to allocate funds here. With the Zanden pieces arguably one of the best digital front-ends currently available, I can't foresee any changes in that department.
Back in the world of the living, I recommend the Resolution Opus 21 and Consonance Droplet CDP-5.0 as two $3K machines that would mesh well with this particular system and even eliminate the need for a preamp. For powerline conditioning, I use two Walker Audio Velocitor S, one for digital, one for analog. At $2,995/ea. without the platform, these aren't cheap but the best I've come across yet if you value jump factor and speed. For considerably less, the BPT PPC strips with Oyaide plugs, optional Bybee filters and ERS cloth that Paul Candy reviewed and purchased could be another consideration at about 1/4 the price.
As Stephæn just found out, the Grand Prix Audio Monaco Modular equipment stand, though $4,000 for a four-tier, is no hare-brained indulgence at all. It's an absolute necessity to optimize the resolving power of the gear you've invested in. There are other solutions (the HRS and Finite Elemente even costlier) but the bottom line is, even experienced audiophiles who simply never dabbled in superior resonance control before are flabbergasted when they finally try out a comprehensive address. In most cases, this will be a far more pronounced and hence senior purchase to make than AC filtration or cabling.
While hornloading properly done seems to bestow additional benefits, the main secret to a life-like, emotionally compelling sound that begins way early on the volume taper is high speaker sensitivity mated to easy load behavior and minimalist electronic networks. On the moons, there's Jeff Day and Marja & Henk with Avantgardes; Michael Lavorgna and Stephæn Harrell with Cain & Cains; and John Potis with Hørning Hybrids. At $2,800, the 101dB/12-ohm Zu Cable Druid offers 40Hz-up performance that is exemplary for the genre to make a perfect entry point for those curious about it. Though not the last word in resolution, the Druid gets all the important things right and furthermore does so without any imbalance. Add $1,500 for a Decware pre/power combo and -- if you're hi-tech -- a hard-drive/DAC-based front end. For a sane amount of scratch (and minus the full bottom octave), you could enjoy great sound that's removed from what I'm listening to merely in terms of ultimate scale but not intrinsic flavor or feel. The ACK Dac, the Wavelength Brick, the AudioZone DAC, the Birdland and others like them are all strong contenders in the value-for-money converter brigade (make sure you're USB compatible if you want to use your computer). When it comes to integrated amplifiers, the 38wpc $999 Onix/Melody SP3 tops my charts with a vengeance. The Eastern Electric kit is another valved bang-for-the-buck proposition that would be right at home here. Naturally, include the li'l Almarro and the RedWine Audio ClariT.
How much has fallen between the cracks and trickled down the drain since I started redoing my big rig? To be honest, I consider it mostly a wash now that the Definitions extend the games to 16Hz stereo. There's certain gains and certain losses but neither are drastic and more along the lines of a minor shift in presentation - adjusted lighting on a scene. One of the most practical listener benefits of the current combo is that the sensation of loud (i.e. fullness) occurs very early on. Low levels are no longer punishment for having been a bad and obnoxious audiophile but simply, all that's necessary to get into the act. Very practical benefits as an audiophile and reviewer? Seeing that $800 amps and $1,000 integrateds can sound phenomenal on the Definitions, I can afford to eventually own a few such amps to cater to the bloody "it sounds good but the same" itch that sometimes compels our kind to tear things apart. The new 30wpc $2,000 FirstWatt Aleph J is high on my could-be list as an example of a traditional Class A transistor amp. The Patek already covers the chip-amp angle and the Taboo the mainstream tube vein by using EL84s. Something like a Fi or Yamamoto could eventually flesh out the exotic tube fringe by way of a 45, 2A3 or even rarer valve. Four different amps for the price of one sure sounds like progress especially to a reviewer when more variety means a greater chance to match up incoming stuff. (Other value/performance-heavy kit can be found in the Hypex, ICEpower and NuForce sector. Perhaps one of their champions can be persuaded to follow Vinnie Rossie's lead and author another analog switching amplifier of low power?)
Naturally, high-eff speakers aren't the only key to the kingdom. The Zus simply cater to my tastes. But the genre in general allows experimentation with small amps (small in power, small in debt guilt) and thus can indulge the hardware-focused Jones of audiophilia that's into equipment for its own sake - because it's cool and gives us a different sonic flavor. Conversely, if all you need to be happy long-term is one amp -- good for you! -- you get to save some serious coin. If you have it to spend regardless, pour it into your front-end to make that as good as possible and/or invest into resonance control. I dare say you would find the whole approach pretty darn rewarding...