@Inkadibass, re. the Tantra I'll only say that I stand by my post #249 (which only applies to the earliest version of the amp -- I have not, like Jake, played subsequent versions) and that, if you have some first-hand experience with the Tantra (or questions about it), you might try posting in either of these recent threads on it, which unfortunately did not get much traction. You might give some exposure to an innovative design from a couple of small builders, thereby:
Sonic Farm Tantra,
Sonic Farm 'Tantra' Demo.
I've not played the Beast, but I own a Zephyr and have played it with a few different poweramps and I played the first version of the Form Factor amp (they're on the second, I believe, which refines the first in a few respects). I did not get to play the two amps back to back (though I did get to directly A/B the FF amp with the Glockenklang Blue Rock I had at the time) and I played them some time apart but, for what it's worth, I found the FF to feel a little more raw and lively than the Glock -- a bit more extended in the deep bass, too -- but less well-behaved. Both amps were loud and hit hard through the Aggie GS410 I tried them through, but the FF seemed to hit a little harder. FF had noticeably more hiss than the Glock (which they might have corrected in the second version of the amp).
Zephyr I'd say is natively smoother than the FF though can get hairier, as well. Much less hiss -- both the amp output and the D.I. are very quiet on mine). I guess the FF is more open and "modern" sounding in the sense of sounding wide -- maybe a bit like a grittier (grit's not necessarily the right word -- it's clean -- but there's something going on -- a little raw and lively in a good way) Euphonic Audio Doubler -- but the Zephyr can get a pretty extended and sweet top end, too (bright switch opens it way up) and it has a very healthy but not insane amount of deep lows on tap.
Re. demos of the Beast, I dunno. There are some clips of the Zephyr out there, including in this thread (some of mine included -- some of those better than others) which should at least give you an idea of the front end.
@scubaduba's
preamp comparison thread featuring the Arkham Oracle also has some nice sound samples with what should be the same core circuitry/sound as the Zephyr/Beast.
The Beast might come across tighter than the Zephyr, courtesy of its internal 24 dB/octave HPF built-in (in addition to the more gentle, higher-voiced HPF selectable from the front panel). I'd rather record with the Zephyr/Beast, I'm almost certain -- I think it's a higher quality execution of a more familiar core sound. For live performance, I guess it'd depend on what you like.
Sorry I can't be more precise -- I'd have to play the FF again (preferably with my cabs -- and, remember, I played the older version) to make a good comparison. Still, I hope it's of some help.
Good luck with your quest!
