There is a general consensus in high end audio (
) that the most significant final audible improvements can be made in drawing down the audio hardware system noise floor. This allows the well reproduced "little sounds" and musical nuances to be heard and appreciated. These are the sounds lost in lower fi, and only through systematic isolation and damping are they revealed as the overall noise floor is reduced. Such isolation is basically either mechanical or electrical, and each type of "noise" are tackled in different ways, but first by identifying their sources. Your first steps are to have good audio hardware with no obvious electrical or mechanical problems of its own. Since isolation benefits are cummulative, there is no sense starting out on estoteric improvements if you haven't fixed a bad transformer hum first.
Spike feet for speakers isolate in two ways. First, they provide solidity and mechanical base to the speaker so that its energy is not lost or distorted by constantly working against a resiliant surface. Secondly, they remove speaker cabinet vibrations from affecting other system components by draining the vibrations into the solid structural flooring. Both functions, obviously, rely upon the availability of solid structural flooring to be coupled with. My #1 system is located on a poured concrete slab, and the effect of spike isolating the speakers was quite dramatic. Not only was their lower frequency response tightened up considerably, but overall audio electronics performance benefited from in large part eliminating the speakers' variable vibration.
Speaker racks, such as the Sanus Audio racks, extend isolation of vibration to your electronics and other hardware. My spike mounted Sanus five shelf was 80# out of the carton, received 60# of graphited #5 steel shot in its vertical tubular members (so as to resemble a big deadfall hammer), and is capped with a 40# marble slab under my Rega Planar 25. Did I mention that weight aids in damping mechanical vibrations and therefore isolation? Each of the Sanus's shelves is point suspended on 4 steel/elastomer/plexiglass isolating shock absorbers. The entire Sanus rack is then spike coupled to the aforementioned concrete slab. Between shelves, I have tried to combine "noise sources" that are used independently. CD players with their high frequency noise producing clocks and DACS, and components with motors are isolated on different shelves. This serves to provide mechanical isolation by both space and avoiding mechnaical contact between the offending components. Your results with less solid flooring structure will be less impressive; this is yet another effect of the room on the sound system.
As has been suggested, depending on the component and the vibration frequency to be isolated, different component aftermarket "feet" have specific applications. In my #1 system specifically, sorbothane "Little Feet" were selected to isolate the Arcam FMJ 23T, and they do their job well. Owners of other quality CDPs are advised to search the review and tweak literature for the aftermarket isolating feet others have found to work well with particular CDPs, noting, however, how the reviewers other system situations may differ from yours.
Isolation and elimination of electrical effects can also provide significant improvement. While some electrical isolation is provided by the space from the grouping of components on rack shelves discussed above, additional electrical isolation was provided in my #1 system's case by several other steps. First, all mechanical electrical connections from the circuit breaker through the speakers were chemically cleaned and conditioned with appropriate CAIG products before being re-assembled with air tight connections with a cryogenically treated hospital grade isolated ground duplex outlet for audio system power only. Secondly, room lighting was re-connected to another household circuit to isolate rf noise from rheostats, ballasts, and the like. Third, I employ a JR-designed power conditioner/surge protector (which I built) to provide filtered electricity to my source components. Fourth, I utilize well designed, moderately priced, and well constructed power cords and interconnects (balanced, where possible) to further control and protect the electrical signals. I like LAT International's best interconnects, although I'm already on record as liking a hybred copper/silver conductor.
Isolation of mechanical and electrical interferences with an audio system is an ongoing process. Not only are some isolation elements of a type whose performance deteriorates over time in the environment and which therefore have to be periodically checked and maintained, but system changes, knowledge, and innovation provide constant demands for isolation improvement. It's a good thing I like this stuff, because otherwise it could drive me crazy. Not the least of this is the volume of product and opinion in the area of isolation. The end user is going to have to consider and analyze some pretty wild claims. I have elected to pursue to 90% to 95% solution, to stick as much as I can to the basics, to have goals and be satisfied with results.
My practical standard for the success of these efforts? That's easy; when SWMBO comes charging in, hotly accusing me of buying all new hardware because she can hear the audible improvements of my tweaks three rooms away, then I've been successful.
