Simon is a long standing member of the community and comes at these matters from a technical standpoint. His recommendation of this Cisco switch from a very large corporation, and available for a very reasonable 2nd hand price should, I would suggest, answer your own suspicions.
My experience is that everything makes a difference, but not necessarily an improvement. On another thread I reported on removing my EMO network isolator. On well recorded track it had a definite positive effect, on less well recorded material it was deleterious, to such an extent that I put it back in.
WRT AC Isolators, John Swenson is pushing another approach, that he links to leakage loops - edited:
Contrary to all "it makes sense to me" thoughts on the subject the way cut down on leakage loop noise with the DAC and pre/power amps is to have the tightest coupling you can get in the AC domain. Since a leakage loop goes through the AC main the higher the impedance in the mains side the higher the noise voltage generated between the boxes. I know the power conditioner is trying to suppress noise on the mains, but the methods frequently used actually increase the impedance between outlets thus increasing the noise from leakage loops.
So to test this hypothesis, try taking the power conditioner out of the system and just use a very simple power strip, no filters, nothing fancy, just outlets connected by wires. This will give a very low impedance between the AC to each power supply, which should cut down on the noise generated by leakage loops. Everything you now have connected to the power conditioner should go into the simple power strip, including all the digital stuff.
I did this in my system (replaced a $1k power conditioner with a $35 power strip and Topaz isolation transformer) and it made a significant improvement is SQ.
JS recommends the Topaz:
The isolation transformer I'm using is a Topaz model, it is a very special transformer. It has extremely low inter-winding capacitance (.005pf according to the manufacturer). Most transformers have two mechanisms that transfer AC from one side to the other: magnetic and capacitive. The magnetic part is low frequency (it is what the 50/60Hz mains signal uses) and the capacitive is high frequency. The combination means that a "normal" transformer lets a lot of high frequency crud through.
With its extremely low capacitiance the Topaz doesn't pass the high frequency crud on the AV main, just the base line frequency and a couple harmonics. Thus it is a very effective noise filter.
In addition it is a very good surge suppressor as well. Most of the energy in high power surges is contained in high frequency components, which get suppressed by the low capacitance, thus it is quite an effective surge suppressor without needing any other special circuits to achieve this.
This isolation transformer keeps noise and surges from the rest of your house and neighborhood out of your audio system and fully preserves your safety ground.
Yes you are correct about the application, the Topaz plugs into the wall, the power strip plugs into it.
My recommendation is to use a simple power strip with NO filtering or surge suppression, the Topaz does it much better than what will come in almost any power strip. I plug EVERYTHING into thepower strip. This dramatically cuts down on the impedance between boxes, significantly lowering noise generated by leakage loops.
Some people will say "but then the noise injected back into the AC mains can go right into other boxes". Yes it can. BUT recent experiments have been pointing to the leakage loops being a significantly greater detriment to ultimate good sound than the injected noise. Of course different systems are different and this may not be true in all systems, but it is looking like this is a good place to start for many systems.