Opinions on Wyred 4 Sound ICE amps

As mentioned, i could not answer on the PFC. Have you looked at JRDGs product sheet?
Anyway, i measured my speakers at minimum 6.5 ohm at the high (tweeter/mid) and 8.5 ohms at low (bass). In my setup the C-500 offers a smoother top but still with slightly enhanced dynamical contrast and resolution than my W4S STI-1000 with PS Audio high end fuses. The W4S sounded slightly more forced and also a bit sharper in the top. I prefer the C-500.
I won't argue, i could easily use a combo of pre/pow (none class D).
I did however find this unit neat and i need not use more inputs than 1, lesser cables etc.
C-500 work very well with Wadia 381. As a system, i think it performs well. I have been at a few private demos. All system setups has been more expensive than mine, but neither offered any all in all improvements to my sadness.

I made the plunge and purchased the Wyred4Sound preamp and SX1000 from Underwood HiFi. They arrived last week well packaged in double boxes with no UPS shipping damage.

Everything worked and the only hot flash of "what is wrong?" occurred when I started the CD player and no sound came out of the speakers (the volume was turned to zero!).

My initial impressions are compared to a Krell S300i integrated amp with 300 wpc/4 ohms and about 300 hours on it.

Generally speaking, to my ear, the Wyred4Sound and the Krell have a similar overall sound. The difference is not as dramatic as when I upgraded to the Krell from a McIntosh MA6300 integrated at 160wpc/4ohm. The change there was very dramatic as the Mac was definitely warmer sounding but with a lot less dynamics than the Krell.

Right out of the box, I can hear more detail with the Wyred4Sound. For example, individual instruments are easier to hear in a mix. Also, it is easier to recognize individual voices in a multipart vocal harmony.

The soundstage is improved. It is wider and better front to back. I often felt while listening to the Krell that the lead vocal and the drums were coming from the same place. With the Wyred4Sound, there is now a separation with vocals in the front and drums in the back.

Also, on the second day of listening, I cranked the volume to 40 which is well below 60 to stay in passive mode on the preamp. I immediately proved the old adage that Maggies love power. The fullness of the sound improved and there was no thought that the Maggies might sound thin as I sometimes had with the Krell. It was louder than what the Krell could play before it overheated and shutdown into protective mode.

I am not sure what I am hearing regarding the bass. It seems to be fuller, but with perhaps a bit less slam. Krell is noted for their bass so this may take some time to determine if there is an improvement.

The edges of the treble with the new Wyrd4Sound are a bit sharp and initially it is not as musical as the Krell. I hope (expect!) these to improve with time.

The W4S owner manuals advise that there will be a major improvement after about 100 hours of operation and another level of improvement at about 200 hours of operation.

ALSO, the manuals make a point to advise strongly that the power should be disconnected before anything is plugged into or out of the amp and pre amp.

So...my initial thought is that I have made a positive change but I wonder about the bass.

Not sure how Wyred compares to Bel Canto in regards to bass, but I recall when I first listened to the BC ref1000m's, I recall wondering where the bass went in that it really sounded like there was virtually none at first. Once my ears adjusted, I realized that it was there in spades like never before, but had a totally different dimensionality to it, mostly in regards to soundstage depth and imaging, and also cleaner and more tightly damped with much greater nuance.

It's pretty much been bass heaven ever since.

To clear things out regarding PFC:

http://jeffrowland.com/knowledgemanager/questions.php?questionid=144

http://jeffrowland.com/knowledgemanager/questions.php?questionid=180

I listened to four or five albums across the weekend and I think that understand at least part of what Mapman is saying.

For me, simply put, there is a lot more to hear. The feeling of being "there" is really improved. The sound is more palpable and I think that the bass is causing that.