tube upgrade for first sound

Yes, it inverts absolute phase. This is different than the out-of-phase
most of us are familiar with in which the imaging out of whack. I
pesonally can't hear the difference with a unit out of absolute phase and
in absolute phase, but I don't really know what to listen for either. Artg,
can you hear the difference?

I can't hear the difference either, and there's the POV that half of all recordings are inverted anyway. But I have my speakeer leads reversed at the amp just the same as Emmannuel Go is quite insistent about this.

And Paul, as many have mentioned, plug it straight into the wall. After a while, you will want to play with aftermarket power cords.

Id be lying if I said I could always hear the difference, but on some, the bass is off. On other recordings, i cant tell. Mostly i bring it to your attention because emmanuel really really feels strongly about it....

No question that FS owners should swap speaker leads according to Emmanuel's suggestion. There is no argument from me on that issue. I'm just really interested to know what to listen for regarding absolute phase. Alex Peychev has an absolute phase switch on his APL Denon3910 that is remote switchable, too. I've switched that thing back and forth a dozen or more times. Sometimes I think I hear a slightly more expansive soundstage. Other times I'm not sure. It's more of a brain teaser for me at this juncture.

Oldpet,
I like my Supratek very much. It is a very musical preamp. I was lucky because a friend had a nearly new Chenin(less than two months old) that I was able to buy immediately when I found out that the H-Cat wasn't my cup of tea. I must say that another preamp on my short list was the First Sound. Best of luck on your audio adventures. Bob