DNA Stratus, V4 vs Woo WA5-LE, Gen 2 vs LTA MZ3

I owned an A&S (branded ZMF) Pendant for some time. I really liked it, but it didn’t pair quite as well with my Utopia as some other amps, largely because of a slight, but perceptible noise floor. However, I haven’t heard A&S’ higher-end offerings which would be more in line with the Stratus or Stellaris, so my experience with the Pendant isn’t really fair.

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Just FWIW, I own the forge (32/300) currently. It unfortunately does hiss with HD800S (and I suspect would with anything ZMF as well) but Utopia are dead silent (though I havent tried the no music crank the vol yet now that I think about it). Not sure why that is as I usually find it goes the other way but :woman_shrugging:

What does the rectifier switch do and how much was the upgrade?

The amp, as “standard” is optimized for a 5U4G, which is directly heated rectifier. You can put in some indirectly heated rectifiers, even without a switch, but it’s not optimized, particularly in terms of noise floor. I used a GZ34 in the demo Stratus (no switch), and it sounded amazing. With the switch, the amp can also operate optimally for indirectly heated rectifiers.

From Donald himself: “Yes, I can add a switch which allows you to switch between directly heated rectifiers and your favorite indirectly heated type. Keep in mind this alternate setting could only be optimized for rectifiers with the cathode tied to pin 2 (GZ34/GZ37) or to pin 8 (422A)”

I paid $300 for this upgrade.

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I’m very happy I got the switch in my stratus as the Mullard 5ar4 has become my favorite tube with warmer geared headphones. They seem to synergize well.

I fav parings are 5ar4 with Aeolus.
And both 5u4g/5ar4 with Verites and Auteurs.

Edit: that’s with the very neutral leaning EML Solid plates. I look forward to trying either or with the Acmes I’m getting soon.

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SO I checked this a couple days ago and there is hum on utopia on the Forge 32 ohm port if the volume is cranked but none at listening levels (even with a silent “track” playing)

EDIT: BTW, I scanned the thread and didnt see it mentioned. Any experience with any of the decware stuff? EDIT: NVM. Found that you havent had one at the beginning of the thread