I happen to be a proud and highly satisfied owner of several of Simaudio's latest Evolution Series fully differential components, i.e., the W-8 dual-mono power amplifier; the P-8 dual-mono preamplifier; and the Andromeda Reference Balanced CD player. [My reference system also includes a Shunyata Hydra-2 (for the W-8); a Hydra-6 (for the front-end components); Induction dynamics ID1 loudspeakers; Shunyata Copperhead and Diamondback Powersnakes; two custom-wired, 20-amp, dedicated/isolated circuits; and Signal Cable Silver Resolution cabling.]
That said, while I was hardly surprised by Kal Rubinson's very positive review of the W-8 power amplifier (nor by JA's very positive benchtest measurements of the W-8), I believe that as it now stands, this review of the W-8 (together with scant mention of the magnificent P-8 preamplifier) doesn't entirely do justice to Simaudio's new Evolution Series, for the following reasons:
1) The review of the W-8 doesn't include the Moon Andromeda Reference Balanced CD player, which is a critical and highly "evolved" part of Simaudio Moon's Evolution Series. Instead (and unfortunately) the review of the W-8 involves only questionable digital sources, those being the rather antiquated Sony XA-9000ES CD/SACD player, along with the Bel Canto PL-1A "universal" player.
This glaring omission of the state-of-the-art Andromeda CD player in Stereophile's review of the W-8 (with scant mention of the P-8) is very troublesome, because it ignores the very real benefits of total system synergy as intended for Moon's Evolution Series components. Had Stereophile taken the time to wait until the W-8 and P-8 could be extensively reviewed in conjunction with the matching Andromeda (Reference) CD player, the opinions of the Evolution Series would likely have been more informed, and far more positive. (Indeed, when a major audio publication such as Stereophile chooses to either ignore or minimize the concept of system synergy as put forth by certain high-end audio manufacturers, it is no wonder that companies such as Spectral tend to just refuse to provide audio publications with samples for review...)
2) In his review of the W-8, KR wrote "...AC current was supplied directly from the wall socket or via the APC S15 and EP-2450 power conditioners..." Well, why not try reviewing the Simaudio Evolution Series gear with some of the non-current-limiting power conditioning products that Simaudio and many other manufacturers highly respect and recommend, such as Shunyata Research?
3) In his review of the W-8, KR mentioned a slight "mid-bass warmth" on several occasions, and further, that adding the matching W-8 preamp ameliorated this greatly. However, given the fact that the W-8 and P-8 were auditioned without the synergistic benefits of the Andromeda CD player (as well as what I would question as being optimal power conditioning under the conditions of the review), I would be very cautious about KR's opinions here. In addition, I will mention that Simaudio's products typically require 200 or more hours of continuous break-in and burn-in until their components begin to reach thermal and sonic stability, yet this review of the W-8 (along with scant mention of the P-8) makes no mention of how long the W-8 (and P-8) were "cooked" until critical listening sessions were conducted and noted.
Finally, I will mention that in general, I've often found any B&W speakers to sound rather syrupy, overly warm, and a bit too colored, particularly in the mid-registers.